Articles de revues : « Protein-tyrosine kinase »

1

Lawrence, David S., et Jinkui Niu. « Protein Kinase InhibitorsThe Tyrosine-Specific Protein Kinases ». Pharmacology & ; Therapeutics 77, n^o 2 (février 1998) : 81–114. http://dx.doi.org/10.1016/s0163-7258(97)00052-1.

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Dailey, D., G. L. Schieven, M. Y. Lim, H. Marquardt, T. Gilmore, J. Thorner et G. S. Martin. « Novel yeast protein kinase (YPK1 gene product) is a 40-kilodalton phosphotyrosyl protein associated with protein-tyrosine kinase activity ». Molecular and Cellular Biology 10, n^o 12 (décembre 1990) : 6244–56. http://dx.doi.org/10.1128/mcb.10.12.6244-6256.1990.

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Extracts of bakers' yeast (Saccharomyces cerevisiae) contain protein-tyrosine kinase activity that can be detected with a synthetic Glu-Tyr copolymer as substrate (G. Schieven, J. Thorner, and G.S. Martin, Science 231:390-393, 1986). By using this assay in conjunction with ion-exchange and affinity chromatography, a soluble tyrosine kinase activity was purified over 8,000-fold from yeast extracts. The purified activity did not utilize typical substrates for mammalian protein-tyrosine kinases (enolase, casein, and histones). The level of tyrosine kinase activity at all steps of each preparation correlated with the content of a 40-kDa protein (p40). Upon incubation of the most highly purified fractions with Mn-ATP or Mg-ATP, p40 was the only protein phosphorylated on tyrosine. Immunoblotting of purified p40 or total yeast extracts with antiphosphotyrosine antibodies and phosphoamino acid analysis of 32P-labeled yeast proteins fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the 40-kDa protein is normally phosphorylated at tyrosine in vivo. 32P-labeled p40 immunoprecipitated from extracts of metabolically labeled cells by affinity-purified anti-p40 antibodies contained both phosphoserine and phosphotyrosine. The gene encoding p40 (YPK1) was cloned from a yeast genomic library by using oligonucleotide probes designed on the basis of the sequence of purified peptides. As deduced from the nucleotide sequence of YPK1, p40 is homologous to known protein kinases, with features that resemble known protein-serine kinases more than known protein-tyrosine kinases. Thus, p40 is a protein kinase which is phosphorylated in vivo and in vitro at both tyrosine and serine residues; it may be a novel type of autophosphorylating tyrosine kinase, a bifunctional (serine/tyrosine-specific) protein kinase, or a serine kinase that is a substrate for an associated tyrosine kinase.

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Dailey, D., G. L. Schieven, M. Y. Lim, H. Marquardt, T. Gilmore, J. Thorner et G. S. Martin. « Novel yeast protein kinase (YPK1 gene product) is a 40-kilodalton phosphotyrosyl protein associated with protein-tyrosine kinase activity. » Molecular and Cellular Biology 10, n^o 12 (décembre 1990) : 6244–56. http://dx.doi.org/10.1128/mcb.10.12.6244.

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Extracts of bakers' yeast (Saccharomyces cerevisiae) contain protein-tyrosine kinase activity that can be detected with a synthetic Glu-Tyr copolymer as substrate (G. Schieven, J. Thorner, and G.S. Martin, Science 231:390-393, 1986). By using this assay in conjunction with ion-exchange and affinity chromatography, a soluble tyrosine kinase activity was purified over 8,000-fold from yeast extracts. The purified activity did not utilize typical substrates for mammalian protein-tyrosine kinases (enolase, casein, and histones). The level of tyrosine kinase activity at all steps of each preparation correlated with the content of a 40-kDa protein (p40). Upon incubation of the most highly purified fractions with Mn-ATP or Mg-ATP, p40 was the only protein phosphorylated on tyrosine. Immunoblotting of purified p40 or total yeast extracts with antiphosphotyrosine antibodies and phosphoamino acid analysis of 32P-labeled yeast proteins fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the 40-kDa protein is normally phosphorylated at tyrosine in vivo. 32P-labeled p40 immunoprecipitated from extracts of metabolically labeled cells by affinity-purified anti-p40 antibodies contained both phosphoserine and phosphotyrosine. The gene encoding p40 (YPK1) was cloned from a yeast genomic library by using oligonucleotide probes designed on the basis of the sequence of purified peptides. As deduced from the nucleotide sequence of YPK1, p40 is homologous to known protein kinases, with features that resemble known protein-serine kinases more than known protein-tyrosine kinases. Thus, p40 is a protein kinase which is phosphorylated in vivo and in vitro at both tyrosine and serine residues; it may be a novel type of autophosphorylating tyrosine kinase, a bifunctional (serine/tyrosine-specific) protein kinase, or a serine kinase that is a substrate for an associated tyrosine kinase.

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Hoekstra, M. F., N. Dhillon, G. Carmel, A. J. DeMaggio, R. A. Lindberg, T. Hunter et J. Kuret. « Budding and fission yeast casein kinase I isoforms have dual-specificity protein kinase activity. » Molecular Biology of the Cell 5, n^o 8 (août 1994) : 877–86. http://dx.doi.org/10.1091/mbc.5.8.877.

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We have examined the activity and substrate specificity of the Saccharomyces cerevisiae Hrr25p and the Schizosaccharomyces pombe Hhp1, Hhp2, and Cki1 protein kinase isoforms. These four gene products are isotypes of casein kinase I (CKI), and the sequence of these protein kinases predicts that they are protein serine/threonine kinases. However, each of these four protein kinases, when expressed in Escherichia coli in an active form, was recognized by anti-phosphotyrosine antibodies. Phosphoamino acid analysis of 32P-labeled proteins showed phosphorylation on serine, threonine, and tyrosine residues. The E. coli produced forms of Hhp1, Hhp2, and Cki1 were autophosphorylated on tyrosine, and both Hhp1 and Hhp2 were capable of phosphorylating the tyrosine-protein kinase synthetic peptide substrate polymer poly-E4Y1. Immune complex protein kinases assays from S. pombe cells showed that Hhp1-containing precipitates were associated with a protein-tyrosine kinase activity, and the Hhp1 present in these immunoprecipitates was phosphorylated on tyrosine residues. Although dephosphorylation of Hhp1 and Hhp2 by Ser/Thr phosphatase had little effect on the specific activity, tyrosine dephosphorylation of Hhp1 and Hhp2 caused a 1.8-to 3.1-fold increase in the Km for poly-E4Y1 and casein. These data demonstrate that four different CKI isoforms from two different yeasts are capable of protein-tyrosine kinase activity and encode dual-specificity protein kinases.

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Creeden, Justin F., Khaled Alganem, Ali S. Imami, F. Charles Brunicardi, Shi-He Liu, Rammohan Shukla, Tushar Tomar, Faris Naji et Robert E. McCullumsmith. « Kinome Array Profiling of Patient-Derived Pancreatic Ductal Adenocarcinoma Identifies Differentially Active Protein Tyrosine Kinases ». International Journal of Molecular Sciences 21, n^o 22 (17 novembre 2020) : 8679. http://dx.doi.org/10.3390/ijms21228679.

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Pancreatic cancer remains one of the most difficult malignancies to treat. Minimal improvements in patient outcomes and persistently abysmal patient survival rates underscore the great need for new treatment strategies. Currently, there is intense interest in therapeutic strategies that target tyrosine protein kinases. Here, we employed kinome arrays and bioinformatic pipelines capable of identifying differentially active protein tyrosine kinases in different patient-derived pancreatic ductal adenocarcinoma (PDAC) cell lines and wild-type pancreatic tissue to investigate the unique kinomic networks of PDAC samples and posit novel target kinases for pancreatic cancer therapy. Consistent with previously described reports, the resultant peptide-based kinome array profiles identified increased protein tyrosine kinase activity in pancreatic cancer for the following kinases: epidermal growth factor receptor (EGFR), fms related receptor tyrosine kinase 4/vascular endothelial growth factor receptor 3 (FLT4/VEGFR-3), insulin receptor (INSR), ephrin receptor A2 (EPHA2), platelet derived growth factor receptor alpha (PDGFRA), SRC proto-oncogene kinase (SRC), and tyrosine kinase non receptor 2 (TNK2). Furthermore, this study identified increased activity for protein tyrosine kinases with limited prior evidence of differential activity in pancreatic cancer. These protein tyrosine kinases include B lymphoid kinase (BLK), Fyn-related kinase (FRK), Lck/Yes-related novel kinase (LYN), FYN proto-oncogene kinase (FYN), lymphocyte cell-specific kinase (LCK), tec protein kinase (TEC), hemopoietic cell kinase (HCK), ABL proto-oncogene 2 kinase (ABL2), discoidin domain receptor 1 kinase (DDR1), and ephrin receptor A8 kinase (EPHA8). Together, these results support the utility of peptide array kinomic analyses in the generation of potential candidate kinases for future pancreatic cancer therapeutic development.

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Boutin, Jean A. « Tyrosine protein kinase assays ». Journal of Chromatography B : Biomedical Sciences and Applications 684, n^o 1-2 (septembre 1996) : 179–99. http://dx.doi.org/10.1016/0378-4347(95)00563-3.

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7

Laneuville, P. « Abl tyrosine protein kinase ». Seminars in Immunology 7, n^o 4 (août 1995) : 255–66. http://dx.doi.org/10.1006/smim.1995.0030.

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8

Stern, D. F., P. Zheng, D. R. Beidler et C. Zerillo. « Spk1, a new kinase from Saccharomyces cerevisiae, phosphorylates proteins on serine, threonine, and tyrosine ». Molecular and Cellular Biology 11, n^o 2 (février 1991) : 987–1001. http://dx.doi.org/10.1128/mcb.11.2.987-1001.1991.

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A Saccharomyces cerevisiae lambda gt11 library was screened with antiphosphotyrosine antibodies in an attempt to identify a gene encoding a tyrosine kinase. A subclone derived from one positive phage was sequenced and found to contain an 821-amino-acid open reading frame that encodes a protein with homology to protein kinases. We tested the activity of the putative kinase by constructing a vector encoding a glutathione-S-transferase fusion protein containing most of the predicted polypeptide. The fusion protein phosphorylated endogenous substrates and enolase primarily on serine and threonine. The gene was designated SPK1 for serine-protein kinase. Expression of the Spk1 fusion protein in bacteria stimulated serine, threonine, and tyrosine phosphorylation of bacterial proteins. These results, combined with the antiphosphotyrosine immunoreactivity induced by the kinase, indicate that Spk1 is capable of phosphorylating tyrosine as well as phosphorylating serine and threonine. In in vitro assays, the fusion protein kinase phosphorylated the synthetic substrate poly(Glu/Tyr) on tyrosine, but the activity was weak compared with serine and threonine phosphorylation of other substrates. To determine if other serine/threonine kinases would phosphorylate poly(Glu/Tyr), we tested calcium/calmodulin-dependent protein kinase II and the catalytic subunit of cyclic AMP-dependent protein kinase. The two kinases had similar tyrosine-phosphorylating activities. These results establish that the functional difference between serine/threonine- and tyrosine-protein kinases is not absolute and suggest that there may be physiological circumstances in which tyrosine phosphorylation is mediated by serine/threonine kinases.

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9

Stern, D. F., P. Zheng, D. R. Beidler et C. Zerillo. « Spk1, a new kinase from Saccharomyces cerevisiae, phosphorylates proteins on serine, threonine, and tyrosine. » Molecular and Cellular Biology 11, n^o 2 (février 1991) : 987–1001. http://dx.doi.org/10.1128/mcb.11.2.987.

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A Saccharomyces cerevisiae lambda gt11 library was screened with antiphosphotyrosine antibodies in an attempt to identify a gene encoding a tyrosine kinase. A subclone derived from one positive phage was sequenced and found to contain an 821-amino-acid open reading frame that encodes a protein with homology to protein kinases. We tested the activity of the putative kinase by constructing a vector encoding a glutathione-S-transferase fusion protein containing most of the predicted polypeptide. The fusion protein phosphorylated endogenous substrates and enolase primarily on serine and threonine. The gene was designated SPK1 for serine-protein kinase. Expression of the Spk1 fusion protein in bacteria stimulated serine, threonine, and tyrosine phosphorylation of bacterial proteins. These results, combined with the antiphosphotyrosine immunoreactivity induced by the kinase, indicate that Spk1 is capable of phosphorylating tyrosine as well as phosphorylating serine and threonine. In in vitro assays, the fusion protein kinase phosphorylated the synthetic substrate poly(Glu/Tyr) on tyrosine, but the activity was weak compared with serine and threonine phosphorylation of other substrates. To determine if other serine/threonine kinases would phosphorylate poly(Glu/Tyr), we tested calcium/calmodulin-dependent protein kinase II and the catalytic subunit of cyclic AMP-dependent protein kinase. The two kinases had similar tyrosine-phosphorylating activities. These results establish that the functional difference between serine/threonine- and tyrosine-protein kinases is not absolute and suggest that there may be physiological circumstances in which tyrosine phosphorylation is mediated by serine/threonine kinases.

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Trojanek, Joanna B., Maria M. Klimecka, Anna Fraser, Grazyna Dobrowolska et Grazyna Muszyńska. « Characterization of dual specificity protein kinase from maize seedlings. » Acta Biochimica Polonica 51, n^o 3 (30 septembre 2004) : 635–47. http://dx.doi.org/10.18388/abp.2004_3549.

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A protein kinase of 57 kDa, able to phosphorylate tyrosine in synthetic substrates pol(Glu4,Tyr1) and a fragment of Src tyrosine kinase, was isolated and partly purified from maize seedlings (Zea mays). The protein kinase was able to phosphorylate exogenous proteins: enolase, caseins, histones and myelin basic protein. Amino acid analysis of phosphorylated casein and enolase, as well as of phosphorylated endogenous proteins, showed that both Tyr and Ser residues were phosphorylated. Phosphotyrosine was also immunodetected in the 57 kDa protein fraction. In the protein fraction there are present 57 kDa protein kinase and enolase. This co-purification suggests that enolase can be an endogenous substrate of the kinase. The two proteins could be resolved by two-dimensional electrophoresis. Specific inhibitors of typical protein-tyrosine kinases had essentially no effect on the activity of the maize enzyme. Staurosporine, a nonspecific inhibitor of protein kinases, effectively inhibited the 57 kDa protein kinase. Also, poly L-lysine and heparin inhibited tyrosine phosphorylation by 57 kDa maize protein kinase. The substrate and inhibitor specificities of the 57 kDa maize protein kinase phosphorylating tyrosine indicate that it is a novel plant dual-specificity protein kinase.

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Mahajan, S., J. Fargnoli, A. L. Burkhardt, S. A. Kut, S. J. Saouaf et J. B. Bolen. « Src family protein tyrosine kinases induce autoactivation of Bruton's tyrosine kinase. » Molecular and Cellular Biology 15, n^o 10 (octobre 1995) : 5304–11. http://dx.doi.org/10.1128/mcb.15.10.5304.

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Bruton's tyrosine kinase (Btk) is tyrosine phosphorylated and enzymatically activated following ligation of the B-cell antigen receptor. These events are temporally regulated, and Btk activation follows that of various members of the Src family of protein tyrosine kinases, thus raising the possibility that Src kinases participate in the Btk activation process. We have evaluated the mechanism underlying Btk enzyme activation and have explored the potential regulatory relationship between Btk and Src protein kinases. We demonstrate in COS transient-expression assays that Btk can be activated through intramolecular autophosphorylation at tyrosine 551 and that Btk autophosphorylation is required for Btk catalytic functions. Coexpression of Btk with members of the Src family of protein tyrosine kinases, but not Syk, led to Btk tyrosine phosphorylation and activation. Using a series of point mutations in Blk (a representative Src protein kinase) and Btk, we show that Src kinases activate Btk through an indirect mechanism that requires membrane association of the Src enzymes as well as functional Btk SH3 and SH2 domains. Our results are compatible with the idea that Src protein tyrosine kinases contribute to Btk activation by indirectly stimulating Btk intramolecular autophosphorylation.

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Lindberg, R. A., et T. Hunter. « cDNA cloning and characterization of eck, an epithelial cell receptor protein-tyrosine kinase in the eph/elk family of protein kinases ». Molecular and Cellular Biology 10, n^o 12 (décembre 1990) : 6316–24. http://dx.doi.org/10.1128/mcb.10.12.6316-6324.1990.

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A human epithelial (HeLa) cDNA library was screened with degenerate oligonucleotides designed to hybridize to highly conserved regions of protein-tyrosine kinases. One cDNA from this screen was shown to contain a putative protein-tyrosine kinase catalytic domain and subsequently used to isolate another cDNA from a human keratinocyte library that encompasses the entire coding region of a 976-amino-acid polypeptide. The predicted protein has an external domain of 534 amino acids with a presumptive N-terminal signal peptide, a transmembrane domain, and a cytoplasmic domain of 418 amino acids that includes a canonical protein-tyrosine kinase catalytic domain. Molecular phylogeny indicates that this protein kinase is closely related to eph and elk and that this receptor family is more closely related to the non-receptor protein-tyrosine kinase families than to other receptor protein-tyrosine kinases. Antibodies raised against a TrpE fusion protein immunoprecipitated a 130-kDa protein that became phosphorylated on tyrosine in immune complex kinase assays, indicating that this protein is a bona fide protein-tyrosine kinase. Analysis of RNA from 13 adult rat organs showed that the eck gene is expressed most highly in tissues that contain a high proportion of epithelial cells, e.g., skin, intestine, lung, and ovary. Several cell lines of epithelial origin were found to express the eck protein kinase at the protein and RNA levels. Immunohistochemical analysis of several rat organs also showed staining in epithelial cells. These observations prompted us to name this protein kinase eck, for epithelial cell kinase.

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Lindberg, R. A., et T. Hunter. « cDNA cloning and characterization of eck, an epithelial cell receptor protein-tyrosine kinase in the eph/elk family of protein kinases. » Molecular and Cellular Biology 10, n^o 12 (décembre 1990) : 6316–24. http://dx.doi.org/10.1128/mcb.10.12.6316.

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A human epithelial (HeLa) cDNA library was screened with degenerate oligonucleotides designed to hybridize to highly conserved regions of protein-tyrosine kinases. One cDNA from this screen was shown to contain a putative protein-tyrosine kinase catalytic domain and subsequently used to isolate another cDNA from a human keratinocyte library that encompasses the entire coding region of a 976-amino-acid polypeptide. The predicted protein has an external domain of 534 amino acids with a presumptive N-terminal signal peptide, a transmembrane domain, and a cytoplasmic domain of 418 amino acids that includes a canonical protein-tyrosine kinase catalytic domain. Molecular phylogeny indicates that this protein kinase is closely related to eph and elk and that this receptor family is more closely related to the non-receptor protein-tyrosine kinase families than to other receptor protein-tyrosine kinases. Antibodies raised against a TrpE fusion protein immunoprecipitated a 130-kDa protein that became phosphorylated on tyrosine in immune complex kinase assays, indicating that this protein is a bona fide protein-tyrosine kinase. Analysis of RNA from 13 adult rat organs showed that the eck gene is expressed most highly in tissues that contain a high proportion of epithelial cells, e.g., skin, intestine, lung, and ovary. Several cell lines of epithelial origin were found to express the eck protein kinase at the protein and RNA levels. Immunohistochemical analysis of several rat organs also showed staining in epithelial cells. These observations prompted us to name this protein kinase eck, for epithelial cell kinase.

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Tan, J. L., et J. A. Spudich. « Developmentally regulated protein-tyrosine kinase genes in Dictyostelium discoideum ». Molecular and Cellular Biology 10, n^o 7 (juillet 1990) : 3578–83. http://dx.doi.org/10.1128/mcb.10.7.3578-3583.1990.

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Dictyostelium discoideum, an organism that undergoes development and that is amenable to biochemical and molecular genetic approaches, is an attractive model organism with which to study the role of tyrosine phosphorylation in cell-cell communication. We report the presence of protein-tyrosine kinase genes in D. discoideum. Screening of a Dictyostelium cDNA expression library with an anti-phosphotyrosine antibody identifies fusion proteins that exhibit protein-tyrosine kinase activity. Two distinct cDNAs were identified and isolated. Though highly homologous to protein kinases in general, these kinases do not exhibit many of the hallmarks of protein-tyrosine kinases of higher eucaryotes. In addition, these genes are developmentally regulated, which suggests a role for tyrosine phosphorylation in controlling Dictyostelium development.

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Tan, J. L., et J. A. Spudich. « Developmentally regulated protein-tyrosine kinase genes in Dictyostelium discoideum. » Molecular and Cellular Biology 10, n^o 7 (juillet 1990) : 3578–83. http://dx.doi.org/10.1128/mcb.10.7.3578.

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Dictyostelium discoideum, an organism that undergoes development and that is amenable to biochemical and molecular genetic approaches, is an attractive model organism with which to study the role of tyrosine phosphorylation in cell-cell communication. We report the presence of protein-tyrosine kinase genes in D. discoideum. Screening of a Dictyostelium cDNA expression library with an anti-phosphotyrosine antibody identifies fusion proteins that exhibit protein-tyrosine kinase activity. Two distinct cDNAs were identified and isolated. Though highly homologous to protein kinases in general, these kinases do not exhibit many of the hallmarks of protein-tyrosine kinases of higher eucaryotes. In addition, these genes are developmentally regulated, which suggests a role for tyrosine phosphorylation in controlling Dictyostelium development.

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BISOTTO, Sandra, et Elizabeth D. FIXMAN. « Src-family tyrosine kinases, phosphoinositide 3-kinase and Gab1 regulate extracellular signal-regulated kinase 1 activation induced by the type A endothelin-1 G-protein-coupled receptor ». Biochemical Journal 360, n^o 1 (8 novembre 2001) : 77–85. http://dx.doi.org/10.1042/bj3600077.

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The multisubstrate docking protein, growth-factor-receptor-bound protein 2-associated binder 1 (Gab1), which is phosphorylated on tyrosine residues following activation of receptor tyrosine kinases and cytokine receptors, regulates cell proliferation, survival and epithelial morphogenesis. Gab1 is also tyrosine phosphorylated following activation of G-protein-coupled receptors (GPCRs) where its function is poorly understood. To elucidate the role of Gab1 in GPCR signalling, we investigated the mechanism by which the type A endothelin-1 (ET-1) GPCR induced tyrosine phosphorylation of Gab1. Tyrosine phosphorylation of Gab1 induced by endothelin-1 was inhibited by PP1, a pharmacological inhibitor of Src-family tyrosine kinases. ET-1-induced Gab1 tyrosine phosphorylation was also inhibited by LY294002, which inhibits phosphoinositide 3-kinase (PI 3-kinase) enzymes. Inhibition of Src-family tyrosine kinases or PI 3-kinase also inhibited ET-1-induced activation of the mitogen activated protein kinase family member, extracellular signal-regulated kinase (ERK) 1. Thus we determined whether Gab1 regulated ET-1-induced ERK1 activation. Overexpression of wild-type Gab1 potentiated ET-1-induced activation of ERK1. Structure–function analyses of Gab1 indicated that mutant forms of Gab1 that do not bind the Src homology (SH) 2 domains of the p85 adapter subunit of PI 3-kinase or the SH2-domain-containing protein tyrosine phosphatase 2 (SHP-2) were impaired in their ability to potentiate ET-1-induced ERK1 activation. Taken together, our data indicate that PI 3-kinase and Src-family tyrosine kinases regulate ET-1-induced Gab1 tyrosine phosphorylation, which, in turn, induces ERK1 activation via PI 3-kinase- and SHP-2-dependent pathways.

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Amatya, Neha, David Yin-wei Lin et Amy H. Andreotti. « Dynamic regulatory features of the protein tyrosine kinases ». Biochemical Society Transactions 47, n^o 4 (8 août 2019) : 1101–16. http://dx.doi.org/10.1042/bst20180590.

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Abstract The SRC, Abelson murine leukemia viral oncogene homolog 1, TEC and C-terminal SRC Kinase families of non-receptor tyrosine kinases (collectively the Src module kinases) mediate an array of cellular signaling processes and are therapeutic targets in many disease states. Crystal structures of Src modules kinases provide valuable insights into the regulatory mechanisms that control activation and generate a framework from which drug discovery can advance. The conformational ensembles visited by these multidomain kinases in solution are also key features of the regulatory machinery controlling catalytic activity. Measurement of dynamic motions within kinases substantially augments information derived from crystal structures. In this review, we focus on a body of work that has transformed our understanding of non-receptor tyrosine kinase regulation from a static view to one that incorporates how fluctuations in conformational ensembles and dynamic motions influence activation status. Regulatory dynamic networks are often shared across and between kinase families while specific dynamic behavior distinguishes unique regulatory mechanisms for select kinases. Moreover, intrinsically dynamic regions of kinases likely play important regulatory roles that have only been partially explored. Since there is clear precedence that kinase inhibitors can exploit specific dynamic features, continued efforts to define conformational ensembles and dynamic allostery will be key to combating drug resistance and devising alternate treatments for kinase-associated diseases.

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Kobayashi, Tomoko, Shun-Ichi Nakamura et Hirohei Yamamura. « Cytosolic Protein-Tyrosine Kinase Activities in Various Rat Tissues ». Annals of Clinical Biochemistry : International Journal of Laboratory Medicine 26, n^o 2 (mars 1989) : 164–68. http://dx.doi.org/10.1177/000456328902600213.

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Suitable assay conditions for the detection of cytosolic protein-tyrosine kinase activities in crude extracts of various rat tissues have been determined. Cytosolic protein-tyrosine kinases showed common characteristics including substrate specificity and divalent cation requirement. Using (Val5) angiotensin II and Mn2+ rather than a src-related synthetic peptide, E11G1, and Mg2+, we obtained higher activities of cytosolic protein-tyrosine kinases. Among various rat tissues tested, spleen, bone marrow, thymus, small intestine, appendix and lung, in decreasing order of total activity, contained high activities of cytosolic protein-tyrosine kinases. These results suggest that the enzyme activities in lymphatic organs and in organs closely related to cell proliferation are high. The assay system described allows the precise measurement of cytosolic protein-tyrosine kinase activity in various rat tissues, both normal and malignant.

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Rivard, N., G. Rydzewska, J. S. Lods et J. Morisset. « Novel model of integration of signaling pathways in rat pancreatic acinar cells ». American Journal of Physiology-Gastrointestinal and Liver Physiology 269, n^o 3 (1 septembre 1995) : G352—G362. http://dx.doi.org/10.1152/ajpgi.1995.269.3.g352.

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Cholecystokinin (CCK) is the major pancreatic secretagogue and acinar cell mitogen. This study was performed to determine by which effector systems CCK regulates tyrosine kinases, phosphatidylinositol (PtdIns) 3-kinase, and phospholipase D (PLD) activities. Pancreatic acini loaded with [3H]myristic acid or [3H]inositol were used to assay PLD and PtdIns 3-kinase. G protein activation with NaF increased particulate and crude cytosolic tyrosine kinase and PLD activities. PLD activation was pertussis toxin sensitive. Inhibition of phospholipase C (PLC) slightly reduced caerulein-stimulated particulate tyrosine kinase and blocked crude cytosolic tyrosine kinase activity without affecting caerulein-induced PLD activity. Ca2+ is an important factor in caerulein stimulation of tyrosine kinase and PLD activities. Protein kinase C and tyrosine kinase inhibition abolished caerulein-activated particulate and crude cytosolic tyrosine kinase and PtdIns 3-kinase activities without any effect on PLD. Wortmannin inhibited PLD and PtdIns 3-kinase activation. Caerulein-induced amylase secretion was partially reduced by tyrosine kinase inhibition, with no effect from wortmannin. Caerulein can stimulate a pertussis toxin-insensitive G protein, leading to particulate tyrosine kinase activation and a Ca(2+)-sensitive cytosolic tyrosine kinase through PLC activation. However, PLD activation by caerulein is pertussis toxin sensitive, cytosolic Ca2+ sensitive, and independent of previous PLC and tyrosine kinase activation.

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Lhoták, V., P. Greer, K. Letwin et T. Pawson. « Characterization of elk, a brain-specific receptor tyrosine kinase ». Molecular and Cellular Biology 11, n^o 5 (mai 1991) : 2496–502. http://dx.doi.org/10.1128/mcb.11.5.2496-2502.1991.

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The elk gene encodes a novel receptorlike protein-tyrosine kinase, which belongs to the eph subfamily. We have previously identified a partial cDNA encompassing the elk catalytic domain (K. Letwin, S.-P. Yee, and T. Pawson, Oncogene 3:621-678, 1988). Using this cDNA as a probe, we have isolated cDNAs spanning the entire rat elk coding sequence. The predicted Elk protein contains all the hallmarks of a receptor tyrosine kinase, including an N-terminal signal sequence, a cysteine-rich extracellular domain, a membrane-spanning segment, a cytoplasmic tyrosine kinase domain, and a C-terminal tail. In both amino acid sequence and overall structure, Elk is most similar to the Eph and Eck protein-tyrosine kinases, suggesting that the eph, elk, and eck genes encode members of a new subfamily of receptorlike tyrosine kinases. Among rat tissues, elk expression appears restricted to brain and testes, with the brain having higher levels of both elk RNA and protein. Elk protein immunoprecipitated from a rat brain lysate becomes phosphorylated on tyrosine in an in vitro kinase reaction, consistent with the prediction that the mammalian elk gene encodes a tyrosine kinase capable of autophosphorylation. The characteristics of the Elk tyrosine kinase suggest that it may be involved in cell-cell interactions in the nervous system.

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Lhoták, V., P. Greer, K. Letwin et T. Pawson. « Characterization of elk, a brain-specific receptor tyrosine kinase. » Molecular and Cellular Biology 11, n^o 5 (mai 1991) : 2496–502. http://dx.doi.org/10.1128/mcb.11.5.2496.

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The elk gene encodes a novel receptorlike protein-tyrosine kinase, which belongs to the eph subfamily. We have previously identified a partial cDNA encompassing the elk catalytic domain (K. Letwin, S.-P. Yee, and T. Pawson, Oncogene 3:621-678, 1988). Using this cDNA as a probe, we have isolated cDNAs spanning the entire rat elk coding sequence. The predicted Elk protein contains all the hallmarks of a receptor tyrosine kinase, including an N-terminal signal sequence, a cysteine-rich extracellular domain, a membrane-spanning segment, a cytoplasmic tyrosine kinase domain, and a C-terminal tail. In both amino acid sequence and overall structure, Elk is most similar to the Eph and Eck protein-tyrosine kinases, suggesting that the eph, elk, and eck genes encode members of a new subfamily of receptorlike tyrosine kinases. Among rat tissues, elk expression appears restricted to brain and testes, with the brain having higher levels of both elk RNA and protein. Elk protein immunoprecipitated from a rat brain lysate becomes phosphorylated on tyrosine in an in vitro kinase reaction, consistent with the prediction that the mammalian elk gene encodes a tyrosine kinase capable of autophosphorylation. The characteristics of the Elk tyrosine kinase suggest that it may be involved in cell-cell interactions in the nervous system.

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Gold, M. R., J. S. Sanghera, J. Stewart et S. L. Pelech. « Selective activation of p42 mitogen-activated protein (MAP) kinase in murine B lymphoma cell lines by membrane immunoglobulin cross-linking. Evidence for protein kinase C-independent and -dependent mechanisms of activation ». Biochemical Journal 287, n^o 1 (1 octobre 1992) : 269–76. http://dx.doi.org/10.1042/bj2870269.

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Cross-linking of membrane immunoglobulin (mIg), the B lymphocyte antigen receptor, with anti-receptor antibodies stimulates tyrosine phosphorylation of a number of proteins, including one of 42 kDa. Proteins with a similar molecular mass are tyrosine-phosphorylated in response to receptor stimulation in other cell types and have been identified as serine/threonine kinases, termed mitogen-activated protein (MAP) kinases or extracellular signal-regulated kinases (ERKs). The MAP kinases constitute a family of related kinases, at least three of which have molecular masses of 40-45 kDa. In this paper we show that mIg cross-linking stimulated the myelin basic protein phosphotransferase activity characteristic of MAP kinase in both mature and immature murine B cell lines. This enzyme activity co-purified on three different columns with a 42 kDa protein that was tyrosine-phosphorylated (pp42) in response to mIg cross-linking and which reacted with a panel of anti-(MAP kinase) antibodies. Although immunoblotting with the anti-(MAP kinase) antibodies showed that these B cell lines expressed both 42 kDa and 44 kDa forms of MAP kinase, only the 42 kDa form was activated and tyrosine-phosphorylated to a significant extent. Activation of protein kinase C (PKC) with phorbol esters also resulted in selective tyrosine phosphorylation and activation of the 42 kDa MAP kinase. This suggested that mIg-induced MAP kinase activation could be due to stimulation of PKC by mIg. However, mIg-stimulated MAP kinase activation and pp42 tyrosine phosphorylation was only partially blocked by a PKC inhibitor, the staurosporine analogue Compound 3. In contrast, Compound 3 completely blocked the ability of phorbol esters to stimulate MAP kinase activity and induce tyrosine phosphorylation of pp42. Thus mIg may activate MAP kinase by both PKC-dependent and -independent mechanisms.

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&NA;. « Bevacizumab/protein tyrosine kinase inhibitors ». Reactions Weekly &NA;, n^o 1389 (février 2012) : 13–14. http://dx.doi.org/10.2165/00128415-201213890-00038.

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Bose, Ron, Marc A. Holbert, Kerry A. Pickin et Philip A. Cole. « Protein tyrosine kinase–substrate interactions ». Current Opinion in Structural Biology 16, n^o 6 (décembre 2006) : 668–75. http://dx.doi.org/10.1016/j.sbi.2006.10.012.

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LANG, Mark L., Yih-Wen CHEN, Li SHEN, Hong GAO, Gillian A. LANG, Terri K. WADE et William F. WADE. « IgA Fc receptor (FcαR) cross-linking recruits tyrosine kinases, phosphoinositide kinases and serine/threonine kinases to glycolipid rafts ». Biochemical Journal 364, n^o 2 (1 juin 2002) : 517–25. http://dx.doi.org/10.1042/bj20011696.

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The human IgA Fc receptor (FcαR, CD89) triggers several important physiological functions, including phagocytosis, NADPH oxidase activation and antigen presentation. Efforts are underway to delineate FcαR signal-transduction pathways that control these functions. In a previous study, we demonstrated that cross-linking of FcαR increased its partitioning into membrane glycolipid rafts and was accompanied by γ-chain-dependent recruitment and phosphorylation of the tyrosine kinases Lck/Yes-related novel protein tyrosine kinase (Lyn) and Bruton's tyrosine kinase (Btk). Here we have performed a more extensive characterization of signalling effectors recruited to rafts on FcαR cross-linking. We demonstrate that in addition to tyrosine kinases Lyn and Btk, FcαR cross-linking also recruits B-lymphocyte kinase (Blk) and spleen tyrosine kinase (Syk) to rafts. We show recruitment of phosphoinositide kinases, including 3-phosphoinositide 3-kinase and phospholipase Cγ2, and serine/threonine kinases such as protein kinase C (PKC) α, PKC∊, and protein kinase B (PKB) α. This suggests that lipid rafts serve as sites for FcαR-triggered recruitment of multiple classes of signalling effectors. We further demonstrate that tyrosine kinases and PKCα have a sustained association with rafts, whereas phosphoinositide 3-kinase and its downstream effectors have a transient association with rafts. This is consistent with temporally regulated divergence of FcαR signalling pathways in rafts. Furthermore, we suggest the spatial separation of signalling effectors by transport of phosphoinositide 3-kinase, phosphoinositide-dependent kinase 1, PKBα and PKC∊ to endocytic compartments containing internalized FcαR.

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Hurley, T. R., R. Hyman et B. M. Sefton. « Differential effects of expression of the CD45 tyrosine protein phosphatase on the tyrosine phosphorylation of the lck, fyn, and c-src tyrosine protein kinases ». Molecular and Cellular Biology 13, n^o 3 (mars 1993) : 1651–56. http://dx.doi.org/10.1128/mcb.13.3.1651-1656.1993.

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Expression of the CD45 tyrosine protein phosphatase is required for the response of functional lymphocytes to stimulation through the antigen receptor. One or more of its substrates may therefore be essential for signal transduction during lymphocyte activation. We have studied the phosphorylation of the closely related lck, fyn, and c-src tyrosine protein kinases in leukemic murine T-cell lines that have lost the expression of CD45. The phosphorylation of the lck kinase at an inhibitory site of tyrosine phosphorylation, Tyr-505, was increased by two-, six-, and eightfold in three different cell lines. Phosphorylation of the fyn kinase at the homologous site, Tyr-531, was unaltered in one of these cell lines, but increased by 2.5-fold in the two others. The phosphorylation of p60c-src at the homologous tyrosine was essentially unchanged in the one CD45-negative cell line in which it was examined. The expression of CD45 therefore regulates the phosphorylation and potentially the activity of the lck and fyn tyrosine protein kinases, but the effect on the lck kinase is much greater than on the fyn kinase. This finding and the observation that CD45 had no effect on the phosphorylation of p60c-src suggest that CD45 exhibits polypeptide substrate specificity in vivo. Additionally, these findings are consistent with the hypothesis that the unresponsiveness of CD45-negative lymphoid cells to antigenic stimulation is due largely to hyperphosphorylation of the lck kinase.

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Hurley, T. R., R. Hyman et B. M. Sefton. « Differential effects of expression of the CD45 tyrosine protein phosphatase on the tyrosine phosphorylation of the lck, fyn, and c-src tyrosine protein kinases. » Molecular and Cellular Biology 13, n^o 3 (mars 1993) : 1651–56. http://dx.doi.org/10.1128/mcb.13.3.1651.

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Expression of the CD45 tyrosine protein phosphatase is required for the response of functional lymphocytes to stimulation through the antigen receptor. One or more of its substrates may therefore be essential for signal transduction during lymphocyte activation. We have studied the phosphorylation of the closely related lck, fyn, and c-src tyrosine protein kinases in leukemic murine T-cell lines that have lost the expression of CD45. The phosphorylation of the lck kinase at an inhibitory site of tyrosine phosphorylation, Tyr-505, was increased by two-, six-, and eightfold in three different cell lines. Phosphorylation of the fyn kinase at the homologous site, Tyr-531, was unaltered in one of these cell lines, but increased by 2.5-fold in the two others. The phosphorylation of p60c-src at the homologous tyrosine was essentially unchanged in the one CD45-negative cell line in which it was examined. The expression of CD45 therefore regulates the phosphorylation and potentially the activity of the lck and fyn tyrosine protein kinases, but the effect on the lck kinase is much greater than on the fyn kinase. This finding and the observation that CD45 had no effect on the phosphorylation of p60c-src suggest that CD45 exhibits polypeptide substrate specificity in vivo. Additionally, these findings are consistent with the hypothesis that the unresponsiveness of CD45-negative lymphoid cells to antigenic stimulation is due largely to hyperphosphorylation of the lck kinase.

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MULLAPUDI, Srinivas R. S., Francis ALI-OSMAN, Jiang SHOU et Kalkunte S. SRIVENUGOPAL. « DNA repair protein O6-alkylguanine-DNA alkyltransferase is phosphorylated by two distinct and novel protein kinases in human brain tumour cells ». Biochemical Journal 351, n^o 2 (10 octobre 2000) : 393–402. http://dx.doi.org/10.1042/bj3510393.

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We showed recently that human O6-alkylguanine-DNA alkyltransferase (AGT), an important target for improving cancer chemotherapy, is a phosphoprotein and that phosphorylation inhibits its activity [Srivenugopal, Mullapudi, Shou, Hazra and Ali-Osman (2000) Cancer Res. 60, 282–287]. In the present study we characterized the cellular kinases that phosphorylate AGT in the human medulloblastoma cell line HBT228. Crude cell extracts used Mg2+ more efficiently than Mn2+ for phosphorylating human recombinant AGT (rAGT) protein. Both [γ-32P]ATP and [γ-32P]GTP served as phosphate donors, with the former being twice as efficient. Specific components known to activate protein kinase A, protein kinase C and calmodulin-dependent kinases did not stimulate the phosphorylation of rAGT. Phosphoaminoacid analysis after reaction in vitro with ATP or GTP showed that AGT was modified at the same amino acids (serine, threonine and tyrosine) as in intact HBT228 cells. Although some of these properties pointed to casein kinase II as a candidate enzyme, known inhibitors and activators of casein kinase II did not affect rAGT phosphorylation. Fractionation of the cell extracts on poly(Glu/Tyr)-Sepharose resulted in the adsorption of an AGT kinase that modified the tyrosine residues and the exclusion of a fraction that phosphorylated AGT on serine and threonine residues. In-gel kinase assays after SDS/PAGE and non-denaturing PAGE revealed the presence of two AGT kinases of 75 and 130kDa in HBT228 cells. The partly purified tyrosine kinase, identified as the 130kDa enzyme by the same assays, was strongly inhibited by tyrphostin 25 but not by genestein. The tyrosine kinase used ATP or GTP to phosphorylate the AGT protein; this reaction inhibited the DNA repair activity of AGT. Evidence that the kinases might physically associate with AGT in cells was also provided. These results demonstrate that two novel cellular protein kinases, a tyrosine kinase and a serine/threonine kinase, both capable of using GTP as a donor, phosphorylate the AGT protein and affect its function. The new kinases might serve as potential targets for strengthening the biochemical modulation of AGT in human tumours.

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Bach, Horacio, Dennis Wong et Yossef Av-Gay. « Mycobacterium tuberculosis PtkA is a novel protein tyrosine kinase whose substrate is PtpA ». Biochemical Journal 420, n^o 2 (13 mai 2009) : 155–62. http://dx.doi.org/10.1042/bj20090478.

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In Mycobacterium tuberculosis, signal transduction is mediated by 11 serine/threonine kinases, but no tyrosine kinases have been identified thus far. The protein encoded by the ORF (open reading frame) Rv2232 has been annotated as a member of the HAD (haloacid dehydrogenase-like hydrolase) superfamily, which includes phosphatases, phosphomanno- and phosphogluco-mutases, and haloacid dehydrogenases. In the present paper, we report, on the basis of biochemical and mutational analyses, that the Rv2232-encoded protein, named protein tyrosine kinase A (PtkA) is a bona fide protein tyrosine kinase. The cognate substrate of PtkA is the secreted protein tyrosine phosphatase A (PtpA).

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Krieg, Thomas, Qining Qin, Elizabeth C. McIntosh, Michael V. Cohen et James M. Downey. « ACh and adenosine activate PI3-kinase in rabbit hearts through transactivation of receptor tyrosine kinases ». American Journal of Physiology-Heart and Circulatory Physiology 283, n^o 6 (1 décembre 2002) : H2322—H2330. http://dx.doi.org/10.1152/ajpheart.00474.2002.

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Adenosine and acetylcholine (ACh) trigger preconditioning through different signaling pathways. We tested whether either could activate myocardial phosphatidylinositol 3-kinase (PI3-kinase), a putative signaling protein in ischemic preconditioning. We used phosphorylation of Akt, a downstream target of PI3-kinase, as a reporter. Exposure of isolated rabbit hearts to ACh increased Akt phosphorylation 2.62 ± 0.33 fold ( P = 0.001), whereas adenosine caused a significantly smaller increase (1.52 ± 0.08 fold). ACh-induced activation of Akt was abolished by the tyrosine kinase blocker genistein indicating at least one tyrosine kinase between the muscarinic receptor and Akt. ACh-induced Akt activation was blocked by the Src tyrosine kinase inhibitor 4-amino-5-(4-chlorophenyl)-7-( t-butyl)pyrazolo[3,4- d]pyrimidine (PP2) and by 4-(3-chloroanilino)-6,7-dimethoxyquinazoline (AG-1478), an epidermal growth factor receptor (EGFR) inhibitor, suggesting phosphorylation of a receptor tyrosine kinase in an Src tyrosine kinase-dependent manner. ACh caused tyrosine phosphorylation of the EGFR, which could be blocked by PP2, thus supporting this receptor hypothesis. AG-1478 failed to block the cardioprotection of ACh, however, suggesting that other receptor tyrosine kinases might be involved. Therefore, Gi protein-coupled receptors can activate PI3-kinase/Akt through transactivation of receptor tyrosine kinases in an Src tyrosine kinase-dependent manner.

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Maher, P. A. « Tissue-dependent regulation of protein tyrosine kinase activity during embryonic development. » Journal of Cell Biology 112, n^o 5 (1 mars 1991) : 955–63. http://dx.doi.org/10.1083/jcb.112.5.955.

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Protein tyrosine kinase activity was assayed in a variety of chicken tissues during embryonic development and in the adult. In some tissues protein tyrosine kinase activity decreased during embryonic development; however, in other tissues it remained high throughout development, it contrast to the level of protein tyrosine phosphorylation, which decreased during development. The highest levels of tyrosine kinase activity were detected in 17-d embryonic brain although only low levels of protein tyrosine phosphorylation were observed in this tissue. Several alternatives were examined in an effort to determine the mechanism responsible for the low levels of tyrosine phosphorylated proteins in most older embryonic and adult chicken tissues despite the presence of highly active tyrosine kinases. The results show that the regulation of protein tyrosine phosphorylation during embryonic development is complex and varies from tissue to tissue. Furthermore, the results suggest that protein tyrosine phosphatases play an important role in regulating the level of phosphotyrosine in proteins of many older embryonic and adult tissues.

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Sanguedolce, M. V., C. Capo, M. Bouhamdan, P. Bongrand, C. K. Huang et J. L. Mege. « Zymosan-induced tyrosine phosphorylations in human monocytes. Role of protein kinase C. » Journal of Immunology 151, n^o 1 (1 juillet 1993) : 405–14. http://dx.doi.org/10.4049/jimmunol.151.1.405.

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Abstract Protein tyrosine phosphorylations are involved in the proliferation and secretory responses of immune cells, but their role in phagocytes is poorly understood. The ability of unopsonized zymosan to induce protein tyrosine phosphorylations was investigated in human monocytes. The addition of zymosan to monocytes resulted in an increase in tyrosine phosphorylation of several endogenous proteins including 28-, 33-, 38-, 42-, 47-, 55- to 60-, 62-, 68-, 90-, 105-, 116-, and 120-kDa proteins; 55- to 60-kDa proteins were the predominant phosphoproteins. Moreover, we studied the effects of tyrphostin 23, a specific tyrosine kinase inhibitor, on stimulated tyrosine phosphorylations and early secretory responses of monocytes, i.e., arachidonic acid release and oxidative metabolism. We showed that tyrphostin inhibited zymosan-stimulated tyrosine phosphorylations and arachidonic acid release, but that it did not affect superoxide generation induced by zymosan. Zymosan binds mainly to CR3 receptor on human monocytes, and CR3 is devoid of intrinsic tyrosine kinase activity. It was predictable that zymosan stimulated a tyrosine kinase distal to the receptor or associated with it. We observed that PMA mimicked zymosan-induced tyrosine phosphorylations, thus suggesting that both agonists used a common transductional pathway implicating the serine/threonine kinase, protein kinase C. The antagonists of protein kinase C, sphingosine and calphostin C, inhibited zymosan-stimulated tyrosine phosphorylations. We suggest that, in human monocytes, zymosan-induced tyrosine phosphorylations are involved in cell responses such as the release of arachidonic acid, and that they require the sequential activation of protein kinase C and cellular protein tyrosine kinases.

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Gutkind, J. S., P. M. Lacal et K. C. Robbins. « Thrombin-dependent association of phosphatidylinositol-3 kinase with p60c-src and p59fyn in human platelets ». Molecular and Cellular Biology 10, n^o 7 (juillet 1990) : 3806–9. http://dx.doi.org/10.1128/mcb.10.7.3806-3809.1990.

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Recent studies have shown that ligand-activated growth factor receptors as well as transforming versions of nonreceptor protein-tyrosine kinases physically associate with phosphatidylinositol-3 kinase (PI-3 kinase). Reasoning that PI-3 kinase might also play a role in the normal functions of nonreceptor kinases, we sought to determine whether association with PI-3 kinase might serve as a measure of nonreceptor protein-tyrosine kinase activation under physiological conditions. We found that p60c-src as well as p59fyn, the product of another member of the src family of proto-oncogenes, physically associated with a PI kinase activity within 5 s after exposure to thrombin. Furthermore, PI kinase reaction products generated in p60v-src, p60c-src or p59fyn containing immunoprecipitates were indistinguishable, demonstrating the identity of the associated enzyme as PI-3 kinase. These findings demonstrate a thrombin-dependent interaction between p60c-src or p59fyn and PI-3 kinase and suggest a role for nonreceptor protein-tyrosine kinases in human platelet signal transduction.

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Gutkind, J. S., P. M. Lacal et K. C. Robbins. « Thrombin-dependent association of phosphatidylinositol-3 kinase with p60c-src and p59fyn in human platelets. » Molecular and Cellular Biology 10, n^o 7 (juillet 1990) : 3806–9. http://dx.doi.org/10.1128/mcb.10.7.3806.

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Recent studies have shown that ligand-activated growth factor receptors as well as transforming versions of nonreceptor protein-tyrosine kinases physically associate with phosphatidylinositol-3 kinase (PI-3 kinase). Reasoning that PI-3 kinase might also play a role in the normal functions of nonreceptor kinases, we sought to determine whether association with PI-3 kinase might serve as a measure of nonreceptor protein-tyrosine kinase activation under physiological conditions. We found that p60c-src as well as p59fyn, the product of another member of the src family of proto-oncogenes, physically associated with a PI kinase activity within 5 s after exposure to thrombin. Furthermore, PI kinase reaction products generated in p60v-src, p60c-src or p59fyn containing immunoprecipitates were indistinguishable, demonstrating the identity of the associated enzyme as PI-3 kinase. These findings demonstrate a thrombin-dependent interaction between p60c-src or p59fyn and PI-3 kinase and suggest a role for nonreceptor protein-tyrosine kinases in human platelet signal transduction.

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K. Bhanumathy, Kalpana, Amrutha Balagopal, Frederick S. Vizeacoumar, Franco J. Vizeacoumar, Andrew Freywald et Vincenzo Giambra. « Protein Tyrosine Kinases : Their Roles and Their Targeting in Leukemia ». Cancers 13, n^o 2 (7 janvier 2021) : 184. http://dx.doi.org/10.3390/cancers13020184.

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Protein kinases constitute a large group of enzymes catalysing protein phosphorylation and controlling multiple signalling events. The human protein kinase superfamily consists of 518 members and represents a complicated system with intricate internal and external interactions. Protein kinases are classified into two main families based on the ability to phosphorylate either tyrosine or serine and threonine residues. Among the 90 tyrosine kinase genes, 58 are receptor types classified into 20 groups and 32 are of the nonreceptor types distributed into 10 groups. Tyrosine kinases execute their biological functions by controlling a variety of cellular responses, such as cell division, metabolism, migration, cell–cell and cell matrix adhesion, cell survival and apoptosis. Over the last 30 years, a major focus of research has been directed towards cancer-associated tyrosine kinases owing to their critical contributions to the development and aggressiveness of human malignancies through the pathological effects on cell behaviour. Leukaemia represents a heterogeneous group of haematological malignancies, characterised by an uncontrolled proliferation of undifferentiated hematopoietic cells or leukaemia blasts, mostly derived from bone marrow. They are usually classified as chronic or acute, depending on the rates of their progression, as well as myeloid or lymphoblastic, according to the type of blood cells involved. Overall, these malignancies are relatively common amongst both children and adults. In malignant haematopoiesis, multiple tyrosine kinases of both receptor and nonreceptor types, including AXL receptor tyrosine kinase (AXL), Discoidin domain receptor 1 (DDR1), Vascular endothelial growth factor receptor (VEGFR), Fibroblast growth factor receptor (FGFR), Mesenchymal–epithelial transition factor (MET), proto-oncogene c-Src (SRC), Spleen tyrosine kinase (SYK) and pro-oncogenic Abelson tyrosine-protein kinase 1 (ABL1) mutants, are implicated in the pathogenesis and drug resistance of practically all types of leukaemia. The role of ABL1 kinase mutants and their therapeutic inhibitors have been extensively analysed in scientific literature, and therefore, in this review, we provide insights into the impact and mechanism of action of other tyrosine kinases involved in the development and progression of human leukaemia and discuss the currently available and emerging treatment options based on targeting these molecules.

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K. Bhanumathy, Kalpana, Amrutha Balagopal, Frederick S. Vizeacoumar, Franco J. Vizeacoumar, Andrew Freywald et Vincenzo Giambra. « Protein Tyrosine Kinases : Their Roles and Their Targeting in Leukemia ». Cancers 13, n^o 2 (7 janvier 2021) : 184. http://dx.doi.org/10.3390/cancers13020184.

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Protein kinases constitute a large group of enzymes catalysing protein phosphorylation and controlling multiple signalling events. The human protein kinase superfamily consists of 518 members and represents a complicated system with intricate internal and external interactions. Protein kinases are classified into two main families based on the ability to phosphorylate either tyrosine or serine and threonine residues. Among the 90 tyrosine kinase genes, 58 are receptor types classified into 20 groups and 32 are of the nonreceptor types distributed into 10 groups. Tyrosine kinases execute their biological functions by controlling a variety of cellular responses, such as cell division, metabolism, migration, cell–cell and cell matrix adhesion, cell survival and apoptosis. Over the last 30 years, a major focus of research has been directed towards cancer-associated tyrosine kinases owing to their critical contributions to the development and aggressiveness of human malignancies through the pathological effects on cell behaviour. Leukaemia represents a heterogeneous group of haematological malignancies, characterised by an uncontrolled proliferation of undifferentiated hematopoietic cells or leukaemia blasts, mostly derived from bone marrow. They are usually classified as chronic or acute, depending on the rates of their progression, as well as myeloid or lymphoblastic, according to the type of blood cells involved. Overall, these malignancies are relatively common amongst both children and adults. In malignant haematopoiesis, multiple tyrosine kinases of both receptor and nonreceptor types, including AXL receptor tyrosine kinase (AXL), Discoidin domain receptor 1 (DDR1), Vascular endothelial growth factor receptor (VEGFR), Fibroblast growth factor receptor (FGFR), Mesenchymal–epithelial transition factor (MET), proto-oncogene c-Src (SRC), Spleen tyrosine kinase (SYK) and pro-oncogenic Abelson tyrosine-protein kinase 1 (ABL1) mutants, are implicated in the pathogenesis and drug resistance of practically all types of leukaemia. The role of ABL1 kinase mutants and their therapeutic inhibitors have been extensively analysed in scientific literature, and therefore, in this review, we provide insights into the impact and mechanism of action of other tyrosine kinases involved in the development and progression of human leukaemia and discuss the currently available and emerging treatment options based on targeting these molecules.

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Jin, N., R. A. Siddiqui, D. English et R. A. Rhoades. « Communication between tyrosine kinase pathway and myosin light chain kinase pathway in smooth muscle ». American Journal of Physiology-Heart and Circulatory Physiology 271, n^o 4 (1 octobre 1996) : H1348—H1355. http://dx.doi.org/10.1152/ajpheart.1996.271.4.h1348.

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Two separate signal transduction pathways exist in vascular smooth muscle: one for cell growth, proliferation, and differentiation and the other for contraction. Although activation of protein tyrosine kinases is intimately involved in the signaling pathway that induces cell growth, proliferation, and differentiation, activation of myosin light chain kinase (MLCK) is an important step in the pathway leading to smooth muscle contraction. Indirect evidence suggests that “cross talk” exists between these two signaling pathways, but the common intermediates are not well defined. The purpose of this study was to determine whether a vasoconstrictor and a mitogen initiate crossover signaling between the tyrosine kinase pathway and the MLCK pathway in vascular smooth muscle. Rat aorta and pulmonary arteries were isolated and stimulated with either fetal calf serum (FCS) or phenylephrine in the presence or absence of a tyrosine kinase inhibitor (genistein) or tyrosine phosphatase inhibitor [sodium o-vanadate (Na3 VO4)]. Isometric force was recorded as a function of time; myosin light chain phosphorylation, protein tyrosine phosphorylation, and mitogen-activated protein kinase (MAPK) mobility were determined by immunoblotting. The results demonstrate that FCS, which contains a variety of growth factors known to activate tyrosine kinases, induced myosin light chain phosphorylation and contraction in vascular smooth muscle. Phenylephrine, a vasoconstrictor known to activate MLCK, induced tyrosine phosphorylation of a 42-kDa protein identified as MAPK. Tyrosine phosphorylation of this protein was inhibited by genistein and enhanced by vanadate. Genistein significantly inhibited both serum- and phenylephrine-induced myosin light chain phosphorylation as well as the serum- and phenylephrine-induced force generation, whereas vanadate enhanced these responses. These data demonstrate interrelationship between activation of the tyrosine kinase pathway and the MLCK pathway in vascular smooth muscle. These interactions may influence smooth muscle contraction and be important in the regulation of smooth muscle cell proliferation.

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Wen, X., H. H. Lin et D. K. Ann. « Salivary Cellular Signaling and Gene Regulation ». Advances in Dental Research 14, n^o 1 (décembre 2000) : 76–80. http://dx.doi.org/10.1177/08959374000140011201.

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Protein tyrosine kinase and protein serine kinase activation has been implicated in the regulation of salivary cell proliferation and differentiation. Aberrant expression and alterations of certain tyrosine or serine kinases, such as Raf or erbB2, are known to trigger salivary tumor development (Li et al., 1997; Cho et al., 1999). It has been estimated that there are about 1000 to 2000 protein kinases in the mammalian genome, with 100 to 200 of them ( i.e., 10%) being tyrosine kinase (Hanks and Hunter, 1995). At present, there are approximately 85 different tyrosine kinases identified in the GenBank database. Based on the relatively slow rate of discovery in the past few years, 100 is a better approximation of the total number of tyrosine kinases encoded by each mammalian genome. It is reasonable to assume that there are about 30 to 50 tyrosine kinases expressed in a given cell at a given differentiation/proliferation stage. This number is large enough to provide a characteristic tissue-specific tyrosine kinase expression profile, but small enough to be identified in a simple screening. The hope for tyrosine kinases as differentiation or proliferation markers rests with the possibility for the identification and characterization of a differentiation/proliferation stage-specific expression pattern in salivary cells. Several ligands that transmit signal through receptor tyrosine kinases and/or Ras/Raf/ERK kinases have been extensively studied in salivary cells. This review focuses mainly on the signaling pathways activated bv Raf and Etk.

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Sharfe, N., HK Dadi et CM Roifman. « JAK3 protein tyrosine kinase mediates interleukin-7-induced activation of phosphatidylinositol-3' kinase ». Blood 86, n^o 6 (15 septembre 1995) : 2077–85. http://dx.doi.org/10.1182/blood.v86.6.2077.bloodjournal8662077.

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The interleukin-7 (IL-7) receptor is expressed throughout T-cell differentiation and, although lacking a tyrosine kinase domain, mediates tyrosine phosphorylation in T cells. We have identified IL-7- induced activation of three cyoplasmic tyrosine kinases in T cells, Jak1, Jak3, and the src-like kinase p56lck. Many members of the cytokine receptor superfamily activate the Jak protein tyrosine kinase family, with resultant phosphorylation of the Stat transcriptional activator factors. We describe here a novel function of the Jak kinases, because Jak kinase activity is not only required for Stat activation but also for P13 kinase response to IL-7 in human T cells. We show that IL-7 receptor-mediated Jak activation can occur independently of p56lck activity. IL-7-induced P13 kinase activation, mediated by tyrosine phosphorylation of the P13 kinase p85 subunit, is essential to the IL-7 proliferative signal and also occurs in the absence of src family kinase activity. Jak3 is found associated with the p85 subunit of P13 kinase in an IL-7-responsive manner in T cells and appears to regulate IL-7-induced P13 kinase activation by mediating tyrosine phosphorylation of the p85 subunit. Specific inhibition of IL- 7-induced Jak kinase activity ablates p85 tyrosine phosphorylation, subsequent P13 kinase activation, and, ultimately, proliferation. The ability to regulate P13 kinase activity indicates a more generalized role for the Jak family than activation of gene transcription via the Stat family in cytokine receptor signal transduction.

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Rane, M. J., S. L. Carrithers, J. M. Arthur, J. B. Klein et K. R. McLeish. « Formyl peptide receptors are coupled to multiple mitogen-activated protein kinase cascades by distinct signal transduction pathways : role in activation of reduced nicotinamide adenine dinucleotide oxidase. » Journal of Immunology 159, n^o 10 (15 novembre 1997) : 5070–78. http://dx.doi.org/10.4049/jimmunol.159.10.5070.

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Abstract Formyl peptide receptor activation of three mitogen-activated protein kinase (MAPK) cascades, extracellular signal-regulated kinases (ERKs), N-terminal kinases (JNKs), and p38 MAPK was examined in differentiated HL-60 granulocytes. FMLP stimulated a concentration- and time-dependent increase in ERK, JNK, and p38 MAPK activities, all of which were dependent on a pertussis toxin-sensitive G protein. Pharmacologic inhibitors were used to examine the roles of tyrosine kinases, phosphatidylinositol 3-kinase, protein kinase C, and phospholipase C. FMLP-stimulated ERK activity was dependent on tyrosine kinases, phosphatidylinositol 3-kinase, protein kinase C, and phospholipase C; p38 MAPK activation was dependent on phosphatidylinositol 3-kinase and phospholipase C; while JNK activation was independent of all of these signaling components. The mitogen-activated protein kinase/ERK kinase inhibitor PD098059 reduced ERK activation by 90%, while an inhibitor of p38 MAPK, SB203580, inhibited p38 MAPK activation by 80%. Both PD098059 and SB203580 inhibited FMLP-stimulated superoxide release, as did inhibitors directed against protein kinase C, tyrosine kinases, and phosphatidylinositol 3-kinase. We conclude that formyl peptide receptors are coupled to three MAPK cascades by Gi proteins. ERKs, p38 MAPK, and JNKs are each activated by distinct proximal signal transduction pathways. Activation of p38 MAPK is necessary for FMLP stimulation of respiratory burst activity; however, a second signal that may involve ERK is also required for this activity.

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Gould, K. L., J. R. Woodgett, C. M. Isacke et T. Hunter. « The protein-tyrosine kinase substrate p36 is also a substrate for protein kinase C in vitro and in vivo ». Molecular and Cellular Biology 6, n^o 7 (juillet 1986) : 2738–44. http://dx.doi.org/10.1128/mcb.6.7.2738-2744.1986.

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p36, a major in vivo substrate of protein-tyrosine kinases, is shown to be phosphorylated at serine 25, a site very close to the major site of tyrosine phosphorylation by pp60v-src, tyrosine 23 (J. R. Glenney, Jr., and B. F. Tack, Proc. Natl. Acad. Sci. USA 82:7884-7888, 1985). We present evidence suggesting that protein kinase C mediates phosphorylation of serine 25.

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Gould, K. L., J. R. Woodgett, C. M. Isacke et T. Hunter. « The protein-tyrosine kinase substrate p36 is also a substrate for protein kinase C in vitro and in vivo. » Molecular and Cellular Biology 6, n^o 7 (juillet 1986) : 2738–44. http://dx.doi.org/10.1128/mcb.6.7.2738.

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p36, a major in vivo substrate of protein-tyrosine kinases, is shown to be phosphorylated at serine 25, a site very close to the major site of tyrosine phosphorylation by pp60v-src, tyrosine 23 (J. R. Glenney, Jr., and B. F. Tack, Proc. Natl. Acad. Sci. USA 82:7884-7888, 1985). We present evidence suggesting that protein kinase C mediates phosphorylation of serine 25.

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Beeler, J. F., W. J. LaRochelle, M. Chedid, S. R. Tronick et S. A. Aaronson. « Prokaryotic expression cloning of a novel human tyrosine kinase ». Molecular and Cellular Biology 14, n^o 2 (février 1994) : 982–88. http://dx.doi.org/10.1128/mcb.14.2.982-988.1994.

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Screening of a human embryonic lung fibroblast cDNA expression library with antiphosphotyrosine antibodies led to isolation of a novel protein kinase. A clone, designated A6, contained a 3-kb cDNA insert with a predicted open reading frame of 350 amino acids. DNA sequence analysis failed to reveal any detectable similarity with previously known genes, and the predicted A6 protein lacked any of the motifs commonly conserved in the catalytic domains of protein kinases. However, the bacterially expressed beta-galactosidase-A6 fusion protein demonstrated both tyrosine and serine phosphorylation in an in vitro kinase assay and phosphorylated exogenous substrates including myelin basic protein specifically on tyrosine residues. The enzyme also displayed biochemical properties analogous to those of other protein tyrosine kinases. The A6 gene was found to be expressed widely at the transcript level in normal tissues and was evolutionarily conserved. Thus, A6 represents a novel tyrosine kinase which is highly divergent from previously described members of this important class of regulatory molecules.

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Beeler, J. F., W. J. LaRochelle, M. Chedid, S. R. Tronick et S. A. Aaronson. « Prokaryotic expression cloning of a novel human tyrosine kinase. » Molecular and Cellular Biology 14, n^o 2 (février 1994) : 982–88. http://dx.doi.org/10.1128/mcb.14.2.982.

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Screening of a human embryonic lung fibroblast cDNA expression library with antiphosphotyrosine antibodies led to isolation of a novel protein kinase. A clone, designated A6, contained a 3-kb cDNA insert with a predicted open reading frame of 350 amino acids. DNA sequence analysis failed to reveal any detectable similarity with previously known genes, and the predicted A6 protein lacked any of the motifs commonly conserved in the catalytic domains of protein kinases. However, the bacterially expressed beta-galactosidase-A6 fusion protein demonstrated both tyrosine and serine phosphorylation in an in vitro kinase assay and phosphorylated exogenous substrates including myelin basic protein specifically on tyrosine residues. The enzyme also displayed biochemical properties analogous to those of other protein tyrosine kinases. The A6 gene was found to be expressed widely at the transcript level in normal tissues and was evolutionarily conserved. Thus, A6 represents a novel tyrosine kinase which is highly divergent from previously described members of this important class of regulatory molecules.

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BRADFORD, Michelle D., et Stephen P. SOLTOFF. « P2X7 receptors activate protein kinase D and p42/p44 mitogen-activated protein kinase (MAPK) downstream of protein kinase C ». Biochemical Journal 366, n^o 3 (15 septembre 2002) : 745–55. http://dx.doi.org/10.1042/bj20020358.

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Protein kinase D (PKD), also called protein kinase Cμ (PKCμ), is a serine/threonine kinase that has unique enzymic and structural properties distinct from members of the PKC family of proteins. In freshly isolated rat parotid acinar salivary cells, extracellular ATP rapidly increased the activity and phosphorylation of PKD. The stimulation by ATP required high concentrations, was mimicked by the P2X7 receptor ligand BzATP [2′- and 3′-O-(4-benzoylbenzoyl)ATP], and was blocked by Mg2+ and 4,4′-di-isothiocyano-2,2′-stilbene disulphonate (DIDS), suggesting that activation of PKD was mediated by P2X7 receptors, which are ligand-gated non-selective cation channels. Phorbol ester (PMA) and the activation of muscarinic and substance P receptors also increased PKD activity. PKC inhibitors blocked ligand-dependent PKD activation and phosphorylation, determined by in vitro phosphorylation studies and by phospho-specific antibodies to two activation loop sites (Ser744 and Ser748) and an autophosphorylation site (Ser916). ATP and BzATP also increased the tyrosine phosphorylation and activity of PKCΔ, and these stimuli also increased extracellular signal-regulated protein kinase (ERK) 1/2 activity in a PKC-dependent manner. PKD activation was not promoted by pervanadate (an inhibitor of tyrosine phosphatases) and was not blocked by PP1 (an inhibitor of Src family kinases) or genistein (a tyrosine kinase inhibitor), suggesting that tyrosine kinases and phosphatases did not play a major role in PKD activation. P2X7 receptor-mediated signalling events were not dependent on Ca2+ entry. These studies indicate that PKC is involved in cellular signalling initiated by P2X7 receptors as well as by G-protein-coupled receptors, and demonstrate that PKD and ERK1/2 are activated in similar PKC-dependent signalling pathways initiated by these diverse receptor types.

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Wurgler-Murphy, S. M., T. Maeda, E. A. Witten et H. Saito. « Regulation of the Saccharomyces cerevisiae HOG1 mitogen-activated protein kinase by the PTP2 and PTP3 protein tyrosine phosphatases. » Molecular and Cellular Biology 17, n^o 3 (mars 1997) : 1289–97. http://dx.doi.org/10.1128/mcb.17.3.1289.

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In response to increases in extracellular osmolarity, Saccharomyces cerevisiae activates the HOG1 mitogen-activated protein kinase (MAPK) cascade, which is composed of a pair of redundant MAPK kinase kinases, namely, Ssk2p and Ssk22p, the MAPK kinase Pbs2p, and the MAPK Hog1p. Hog1p is activated by Pbs2p through phosphorylation of specific threonine and tyrosine residues. Activated Hog1p is essential for survival of yeast cells at high osmolarity. However, expression of constitutively active mutant kinases, such as those encoded by SSK2deltaN and PBS2(DD), is toxic and results in a lethal level of Hog1p activation. Overexpression of the protein tyrosine phosphatase Ptp2p suppresses the lethality of these mutations by dephosphorylating Hog1p. A catalytically inactive Cys-to-Ser Ptp2p mutant (Ptp2(C/S)p) is tightly bound to tyrosine-phosphorylated Hog1p in vivo. Disruption of PTP2 leads to elevated levels of tyrosine-phosphorylated Hog1p following exposure of cells to high osmolarity. Disruption of both PTP2 and another protein tyrosine phosphatase gene, PTP3, results in constitutive Hog1p tyrosine phosphorylation even in the absence of increased osmolarity. Thus, Ptp2p and Ptp3p are the major phosphatases responsible for the tyrosine dephosphorylation of Hog1p. When catalytically inactive Hog1(K/N)p is expressed in hog1delta cells, it is constitutively tyrosine phosphorylated. In contrast, Hog1(K/N)p, expressed together with wild-type Hog1p, is tyrosine phosphorylated only when cells are exposed to high osmolarity. Thus, the kinase activity of Hog1p is required for its own tyrosine dephosphorylation. Northern blot analyses suggest that Hog1p regulates Ptp2p and/or Ptp3p activity at the posttranscriptional level.

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Wang, Bing, Serge Lemay, Schickwann Tsai et André Veillette. « SH2 Domain-Mediated Interaction of Inhibitory Protein Tyrosine Kinase Csk with Protein Tyrosine Phosphatase-HSCF ». Molecular and Cellular Biology 21, n^o 4 (15 février 2001) : 1077–88. http://dx.doi.org/10.1128/mcb.21.4.1077-1088.2001.

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ABSTRACT The protein tyrosine kinase (PTK) Csk is a potent negative regulator of several signal transduction processes, as a consequence of its exquisite ability to inactivate Src-related PTKs. This function requires not only the kinase domain of Csk, but also its Src homology 3 (SH3) and SH2 regions. We showed previously that the Csk SH3 domain mediates highly specific associations with two members of the PEP family of nonreceptor protein tyrosine phosphatases (PTPs), PEP and PTP-PEST. In comparison, the Csk SH2 domain interacts with several tyrosine phosphorylated molecules, presumed to allow targetting of Csk to sites of Src family kinase activation. Herein, we attempted to understand better the regulation of Csk by identifying ligands for its SH2 domain. Using a modified yeast two-hybrid screen, we uncovered the fact that Csk associates with PTP-HSCF, the third member of the PEP family of PTPs. This association was documented not only in yeast cells but also in a heterologous mammalian cell system and in cytokine-dependent hemopoietic cells. Surprisingly, the Csk–PTP-HSCF interaction was found to be mediated by the Csk SH2 domain and two putative sites of tyrosine phosphorylation in the noncatalytic portion of PTP-HSCF. Transfection experiments indicated that Csk and PTP-HSCF synergized to inhibit signal transduction by Src family kinases and that this cooperativity was dependent on the domains mediating their association. Finally, we obtained evidence that PTP-HSCF inactivated Src-related PTKs by selectively dephosphorylating the positive regulatory tyrosine in their kinase domain. Taken together, these results demonstrate that part of the function of the Csk SH2 domain is to mediate an inducible association with a PTP, thereby engineering a more efficient inhibitory mechanism for Src-related PTKs. Coupled with previously published observations, these data also establish that Csk forms complexes with all three known members of the PEP family.

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Ferrell, J. E., et G. S. Martin. « Identification of a 42-kilodalton phosphotyrosyl protein as a serine(threonine) protein kinase by renaturation ». Molecular and Cellular Biology 10, n^o 6 (juin 1990) : 3020–26. http://dx.doi.org/10.1128/mcb.10.6.3020-3026.1990.

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We have surveyed fibroblast lysates for protein kinases that might be involved in mitogenesis. The assay we have used exploits the ability of blotted, sodium dodecyl sulfate-denatured proteins to regain enzymatic activity after guanidine treatment. About 20 electrophoretically distinct protein kinases could be detected by this method in lysates from NIH 3T3 cells. One of the kinases, a 42-kilodalton serine(threonine) kinase (PK42), was found to possess two- to fourfold-higher in vitro activity when isolated from serum-stimulated cells than when isolated from serum-starved cells. This kinase comigrated on sodium dodecyl sulfate-gels with a protein (p42) whose phosphotyrosine content increased in response to serum stimulation. The time courses of p42 tyrosine phosphorylation and PK42 activation were similar, reaching maximal levels within 10 min and returning to basal levels within 5 h. Both p42 tyrosine phosphorylation and PK42 activation were stimulated by low concentrations of phorbol esters, and the responses of p42 and PK42 to TPA were abolished by chronic 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment. Chronic TPA treatment had less effect on serum-induced p42 tyrosine phosphorylation and PK42 activation. PK42 and p42 bound to DEAE-cellulose, and both eluted at a salt concentration of 250 mM. Thus, PK42 and p42 comigrate and cochromatograph, and the kinase activity of PK42 correlates with the tyrosine phosphorylation of p42. These findings suggest that PK42 and p42 are related or identical, that PK42 is activated by tyrosine phosphorylation, and that this tyrosine phosphorylation can be regulated by protein kinase C.

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Ferrell, J. E., et G. S. Martin. « Identification of a 42-kilodalton phosphotyrosyl protein as a serine(threonine) protein kinase by renaturation. » Molecular and Cellular Biology 10, n^o 6 (juin 1990) : 3020–26. http://dx.doi.org/10.1128/mcb.10.6.3020.

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We have surveyed fibroblast lysates for protein kinases that might be involved in mitogenesis. The assay we have used exploits the ability of blotted, sodium dodecyl sulfate-denatured proteins to regain enzymatic activity after guanidine treatment. About 20 electrophoretically distinct protein kinases could be detected by this method in lysates from NIH 3T3 cells. One of the kinases, a 42-kilodalton serine(threonine) kinase (PK42), was found to possess two- to fourfold-higher in vitro activity when isolated from serum-stimulated cells than when isolated from serum-starved cells. This kinase comigrated on sodium dodecyl sulfate-gels with a protein (p42) whose phosphotyrosine content increased in response to serum stimulation. The time courses of p42 tyrosine phosphorylation and PK42 activation were similar, reaching maximal levels within 10 min and returning to basal levels within 5 h. Both p42 tyrosine phosphorylation and PK42 activation were stimulated by low concentrations of phorbol esters, and the responses of p42 and PK42 to TPA were abolished by chronic 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment. Chronic TPA treatment had less effect on serum-induced p42 tyrosine phosphorylation and PK42 activation. PK42 and p42 bound to DEAE-cellulose, and both eluted at a salt concentration of 250 mM. Thus, PK42 and p42 comigrate and cochromatograph, and the kinase activity of PK42 correlates with the tyrosine phosphorylation of p42. These findings suggest that PK42 and p42 are related or identical, that PK42 is activated by tyrosine phosphorylation, and that this tyrosine phosphorylation can be regulated by protein kinase C.

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Chen, F., M. Torres et R. F. Duncan. « Activation of mitogen-activated protein kinase by heat shock treatment in Drosophila ». Biochemical Journal 312, n^o 2 (1 décembre 1995) : 341–49. http://dx.doi.org/10.1042/bj3120341.

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Heat shock treatment of Drosophila melanogaster tissue culture cells causes increased tyrosine phosphorylation of several 44 kDa proteins, which are identified as Drosophila mitogen-activated protein (MAP) kinases. Tyrosine phosphorylation occurs within 5 min, and is maintained at high levels during heat shock. It decreases to basal levels during recovery, concurrent with the repression of heat shock transcription and heat-shock-protein synthesis. The increased MAP kinase tyrosine phosphorylation is parallelled by increased MAP kinase activity. At least two MAP kinases, DmERK-A and DmERK-B, are identified whose tyrosine phosphorylation increases during heat shock. Thus MAP kinase activation is an immediate early response to heat shock, and its increased activity is maintained throughout heat shock treatment. Protracted MAP kinase activation may contribute to heat shock transcription factor phosphorylation and the numerous metabolic alterations that constitute the heat-shock response.

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