Artigos de revistas: "Carbohydrate receptors"

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Rauschenberg, Melanie, Sateesh Bandaru, Mark P. Waller e Bart Jan Ravoo. "Peptide-Based Carbohydrate Receptors". Chemistry - A European Journal 20, n.º 10 (13 de fevereiro de 2014): 2770–82. http://dx.doi.org/10.1002/chem.201303777.

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Nosova, A. S., Yu A. Budanova e Yu L. Sebyakin. "Structural features of synthetic glycoconjugates and efficiency of their interaction with glycoprotein receptors on the surface of hepatocytes". Fine Chemical Technologies 14, n.º 5 (14 de novembro de 2019): 7–20. http://dx.doi.org/10.32362/2410-6593-2019-14-5-7-20.

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Objectives. Over the last few years, medicinal chemistry research has been focusing on the creation of molecules that can target particular body systems, organs and tissues, thus abating systemic toxicity and side effects, and, most of all, boosting therapeutic potential. This goal can be achieved through the specific interaction of such drugs with active sites of cellular receptors. For example, glycoprotein receptors that can be found on cellular surfaces in neural tissues and liver parenchyma, selectively bind various glycoproteins and glycosides, facilitating their penetration into cells. This review describes how certain parameters of ligand structure (the nature and length of the spacer between carbohydrate and non-carbohydrate fragments of the molecule, number of carbohydrate residues per molecule, etc.) influence the penetration efficiency of synthetic glycoconjugates into liver cells.Methods. This review article summarizes 75 research papers and discusses data from in vitro and in vivo experiments showing which structures of synthetic carbohydrate derivatives are optimal for targeted drug delivery into liver cells.Results. The surface of liver cells (hepatocytes) contains a significant number of asialoglycoprotein receptors (ASGP-R) that are almost never found elsewhere. This makes ASGP-R an ideal target for the directed treatment of liver diseases, including such difficult, socially important conditions as hepatocellular carcinoma and Hepatitis C. A number of various ligands and targeted (to ASGP-R) delivery systems have been designed. Such molecules always contain derivatives of mono- and disaccharides, most commonly D-glucose, D-galactose, D-lactose and N-acetylglucosamines. This review contains the chemical structures of carbohydrate-based ligands.Conclusions. Glycolipids based on D-carbohydrates, when in liposomes, facilitate penetration into liver cells by a receptor-mediated, clathrin-dependent endocytosis mechanism that is activated upon contact of the carbohydrate-containing ligand fragment with the active site of ASGP-R. It can be addressed by the use of monovalent derivatives of carbohydrates as well as polyvalent glycoconjugates. Alterations in the ligand structure and the number of liposomal modifications can boost the therapeutic effect. The distance between the liposomal surface and the carbohydrate residue (spacer length), as well as the hydrophilic-lipophilic balance of the ligand molecule, have a great effect on the affinity and cellular response.

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Bonar-Law, Richard P., Anthony P. Davis e Brian A. Murray. "Artificial Receptors for Carbohydrate Derivatives". Angewandte Chemie International Edition in English 29, n.º 12 (dezembro de 1990): 1407–8. http://dx.doi.org/10.1002/anie.199014071.

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Castillo, Gaston, Ralf Kleene, Melitta Schachner, Gabriele Loers e Andrew E. Torda. "Proteins Binding to the Carbohydrate HNK-1: Common Origins?" International Journal of Molecular Sciences 22, n.º 15 (29 de julho de 2021): 8116. http://dx.doi.org/10.3390/ijms22158116.

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The human natural killer (HNK-1) carbohydrate plays important roles during nervous system development, regeneration after trauma and synaptic plasticity. Four proteins have been identified as receptors for HNK-1: the laminin adhesion molecule, high-mobility group box 1 and 2 (also called amphoterin) and cadherin 2 (also called N-cadherin). Because of HNK-1′s importance, we asked whether additional receptors for HNK-1 exist and whether the four identified proteins share any similarity in their primary structures. A set of 40,000 sequences homologous to the known HNK-1 receptors was selected and used for large-scale sequence alignments and motif searches. Although there are conserved regions and highly conserved sites within each of these protein families, there was no sequence similarity or conserved sequence motifs found to be shared by all families. Since HNK-1 receptors have not been compared regarding binding constants and since it is not known whether the sulfated or non-sulfated part of HKN-1 represents the structurally crucial ligand, the receptors are more heterogeneous in primary structure than anticipated, possibly involving different receptor or ligand regions. We thus conclude that the primary protein structure may not be the sole determinant for a bona fide HNK-1 receptor, rendering receptor structure more complex than originally assumed.

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Kingsley, D. M., K. F. Kozarsky, M. Segal e M. Krieger. "Three types of low density lipoprotein receptor-deficient mutant have pleiotropic defects in the synthesis of N-linked, O-linked, and lipid-linked carbohydrate chains." Journal of Cell Biology 102, n.º 5 (1 de maio de 1986): 1576–85. http://dx.doi.org/10.1083/jcb.102.5.1576.

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Biochemical, immunological, and genetic techniques were used to investigate the genetic defects in three types of low density lipoprotein (LDL) receptor-deficient hamster cells. The previously isolated ldlB, ldlC, and ldlD mutants all synthesized essentially normal amounts of a 125,000-D precursor form of the LDL receptor, but were unable to process this receptor to the mature form of 155,000 D. Instead, these mutants produced abnormally small, heterogeneous receptors that reached the cell surface but were rapidly degraded thereafter. The abnormal sizes of the LDL receptors in these cells were due to defective processing of the LDL receptor's N- and O-linked carbohydrate chains. Processing defects in these cells appeared to be general since the ldlB, ldlC, and ldlD mutants also showed defective glycosylation of a viral glycoprotein, alterations in glycolipid synthesis, and changes in resistance to several toxic lectins. Preliminary structural studies suggested that these cells had defects in multiple stages of the Golgi-associated processing reactions responsible for synthesis of glycolipids and in the N-linked and O-linked carbohydrate chains of glycoproteins. Comparisons between the ldl mutants and a large number of previously isolated CHO glycosylation defective mutants showed that the genetic defects in ldlB, ldlC, and ldlD cells were unique and that only very specific types of carbohydrate alteration could dramatically affect LDL receptor function.

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Bashiri, Sahra, Prashamsa Koirala, Istvan Toth e Mariusz Skwarczynski. "Carbohydrate Immune Adjuvants in Subunit Vaccines". Pharmaceutics 12, n.º 10 (14 de outubro de 2020): 965. http://dx.doi.org/10.3390/pharmaceutics12100965.

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Modern subunit vaccines are composed of antigens and a delivery system and/or adjuvant (immune stimulator) that triggers the desired immune responses. Adjuvants mimic pathogen-associated molecular patterns (PAMPs) that are typically associated with infections. Carbohydrates displayed on the surface of pathogens are often recognized as PAMPs by receptors on antigen-presenting cells (APCs). Consequently, carbohydrates and their analogues have been used as adjuvants and delivery systems to promote antigen transport to APCs. Carbohydrates are biocompatible, usually nontoxic, biodegradable, and some are mucoadhesive. As such, carbohydrates and their derivatives have been intensively explored for the development of new adjuvants. This review assesses the immunological functions of carbohydrate ligands and their ability to enhance systemic and mucosal immune responses against co-administered antigens. The role of carbohydrate-based adjuvants/delivery systems in the development of subunit vaccines is discussed in detail.

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Sørensen, Anne Louise Tølbøll, Henrik Clausen e Hans H. Wandall. "Carbohydrate clearance receptors in transfusion medicine". Biochimica et Biophysica Acta (BBA) - General Subjects 1820, n.º 11 (novembro de 2012): 1797–808. http://dx.doi.org/10.1016/j.bbagen.2012.07.008.

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Das, Goutam, e Andrew D. Hamilton. "Carbohydrate recognition: Enantioselective spirobifluorene diphosphonate receptors". Tetrahedron Letters 38, n.º 21 (maio de 1997): 3675–78. http://dx.doi.org/10.1016/s0040-4039(97)00725-9.

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Rauschenberg, Melanie, Susanne Bomke, Uwe Karst e Bart Jan Ravoo. "Dynamic Peptides as Biomimetic Carbohydrate Receptors". Angewandte Chemie International Edition 49, n.º 40 (26 de agosto de 2010): 7340–45. http://dx.doi.org/10.1002/anie.201002847.

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Cervantes-Olivier, P., C. Delavier-Klutchko, O. Durieu-Trautmann, S. Kaveri, M. Desmandril e A. D. Strosberg. "The β2-adrenergic receptors of human epidermoid carcinoma cells bear two different types of oligosaccharides which influence expression on the cell surface". Biochemical Journal 250, n.º 1 (15 de fevereiro de 1988): 133–43. http://dx.doi.org/10.1042/bj2500133.

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The beta 2-adrenergic receptors of the human epidermoid carcinoma A431 cells reside on two polypeptide chains revealed by photoaffinity labelling with [125I]iodocyanopindolol-diazirine. These proteins correspond to two distinct populations of N-asparagine-linked glycoproteins: the 55-52 kDa molecules are associated with complex carbohydrate chain(s), the 65-63 kDa component with polymannosidic carbohydrate chain(s). Both types of receptors are present in preconfluent cells, but only the polymannosidic type is found in the postconfluent cells. Moreover, complex chains appear to be associated with the receptors with the highest affinity for (-)-isoproterenol and polymannosidic chains with the receptors with the lowest affinity for this agonist. the carbohydrate moiety of the beta-adrenergic receptor is involved in the expression and function of the beta 2-adrenergic receptors at the surface of the A431 cells, since tunicamycin and monensin, complete and partial inhibitors of glycosylation respectively, diminish the number of binding sites at the cell surface and increase the total number of sites in the cell. In these conditions a diminution of cyclic AMP accumulation is also observed.

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Chakraborty, Rila, Prasanta Chakraborty e Mukul K. Basu. "Macrophage Mannosyl Fucosyl Receptor: Its Role in Invasion of Virulent and Avirulent L. Donovani Promastigotes". Bioscience Reports 18, n.º 3 (1 de junho de 1998): 129–42. http://dx.doi.org/10.1023/a:1020192512001.

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The interaction of leishmania parasites with macrophages is known to be receptor mediated. Previous study from this laboratory (J. Parasitol. 82:632, 1996) showed the significant involvement of LPG and gp63 receptors in the recognition of virulent strains onto the macrophages. The role of carbohydrate receptors–the other major receptors besides LPG and gp63 receptors, in the recognition of both virulent (strains AG83 and GE1) and avirulent (strain UR6) leishmania onto the host macrophages has been the major focus of the present investigation. Various neoglycoproteins were used as efficient ligands to preblock the carbohydrate receptors on the macrophage surface. Similarly, various sugar specific lectins were used to preblock the corresponding carbohydrate ligands on the parasite surface. When these preblocked macrophages or parasites were used to study their mode of recognition, it was obvious from the findings that avirulent leishmania promastigotes possibly use the mannosyl fucosyl receptors (MFR) more avidly for their initial attachment and subsequent internalization into the macrophages whereas the virulent leishmania exhibits limited use of this receptor. When a macrophage-like cell line (J774), lacking in MFR, was purposely selected to test the previous findings, as expected, the attachment of avirulent promastigotes (UR6) onto the cell line was found to be negligible when compared to the peritoneal macrophages. Thus, it appears that avirulent leishmania promastigotes probably utilize MFR significantly for their initial recognition and subsequent internalization by macrophages.

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Davis, Anthony P. "Biomimetic carbohydrate recognition". Chemical Society Reviews 49, n.º 9 (2020): 2531–45. http://dx.doi.org/10.1039/c9cs00391f.

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Burzyńska, Patrycja, Łukasz F. Sobala, Krzysztof Mikołajczyk, Marlena Jodłowska e Ewa Jaśkiewicz. "Sialic Acids as Receptors for Pathogens". Biomolecules 11, n.º 6 (2 de junho de 2021): 831. http://dx.doi.org/10.3390/biom11060831.

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Carbohydrates have long been known to mediate intracellular interactions, whether within one organism or between different organisms. Sialic acids (Sias) are carbohydrates that usually occupy the terminal positions in longer carbohydrate chains, which makes them common recognition targets mediating these interactions. In this review, we summarize the knowledge about animal disease-causing agents such as viruses, bacteria and protozoa (including the malaria parasite Plasmodium falciparum) in which Sias play a role in infection biology. While Sias may promote binding of, e.g., influenza viruses and SV40, they act as decoys for betacoronaviruses. The presence of two common forms of Sias, Neu5Ac and Neu5Gc, is species-specific, and in humans, the enzyme converting Neu5Ac to Neu5Gc (CMAH, CMP-Neu5Ac hydroxylase) is lost, most likely due to adaptation to pathogen regimes; we discuss the research about the influence of malaria on this trait. In addition, we present data suggesting the CMAH gene was probably present in the ancestor of animals, shedding light on its glycobiology. We predict that a better understanding of the role of Sias in disease vectors would lead to more effective clinical interventions.

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Kozarsky, K. F., S. M. Call, S. K. Dower e M. Krieger. "Abnormal intracellular sorting of O-linked carbohydrate-deficient interleukin-2 receptors". Molecular and Cellular Biology 8, n.º 8 (agosto de 1988): 3357–63. http://dx.doi.org/10.1128/mcb.8.8.3357-3363.1988.

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The synthesis and intracellular sorting of the interleukin-2 (IL-2) receptor were studied with a line of mutant Chinese hamster ovary (CHO) cells with a reversible defect in protein O glycosylation. Under normal culture conditions the mutant ldlD cannot add N-acetylgalactosamine (Ga1NAc) to proteins. Ga1NAc is the first sugar of mucin-type O-linked oligosaccharides attached to protein. This O-glycosylation defect is rapidly corrected when Ga1NAc is added to the culture mediu. An expression vector for the p55 human IL-2 receptor was transfected into wild-type CHO and ldlD cells and the structure, stability, and cell surface expression of the receptor were examined by immunoprecipitation and antibody-binding assays. Essentially all of the mature form of the normally glycosylated IL-2 receptor in both wild-type CHO cells and ldlD cells incubated with Ga1NAc was expressed on the cell surface. The stability of O-linked carbohydrate-deficient (Od) IL-2 receptors (in ldlD cells without Ga1NAc) was normal; however, missorting of the Od receptors resulted in very little cell surface expression. The sialidase sensitivity and endoglycosidase H resistance of mature Od IL-2 receptors suggest that Od receptor missorting occurred in or beyond the trans Golgi apparatus. The abnormal sorting of the Od IL-2 receptor is compared with the O-glycosylation dependence of the surface expression and stability of the low-density lipoprotein receptor, decay-accelerating factor, and the major antigen envelope protein of Epstein-Barr virus.

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Kozarsky, K. F., S. M. Call, S. K. Dower e M. Krieger. "Abnormal intracellular sorting of O-linked carbohydrate-deficient interleukin-2 receptors." Molecular and Cellular Biology 8, n.º 8 (agosto de 1988): 3357–63. http://dx.doi.org/10.1128/mcb.8.8.3357.

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The synthesis and intracellular sorting of the interleukin-2 (IL-2) receptor were studied with a line of mutant Chinese hamster ovary (CHO) cells with a reversible defect in protein O glycosylation. Under normal culture conditions the mutant ldlD cannot add N-acetylgalactosamine (Ga1NAc) to proteins. Ga1NAc is the first sugar of mucin-type O-linked oligosaccharides attached to protein. This O-glycosylation defect is rapidly corrected when Ga1NAc is added to the culture mediu. An expression vector for the p55 human IL-2 receptor was transfected into wild-type CHO and ldlD cells and the structure, stability, and cell surface expression of the receptor were examined by immunoprecipitation and antibody-binding assays. Essentially all of the mature form of the normally glycosylated IL-2 receptor in both wild-type CHO cells and ldlD cells incubated with Ga1NAc was expressed on the cell surface. The stability of O-linked carbohydrate-deficient (Od) IL-2 receptors (in ldlD cells without Ga1NAc) was normal; however, missorting of the Od receptors resulted in very little cell surface expression. The sialidase sensitivity and endoglycosidase H resistance of mature Od IL-2 receptors suggest that Od receptor missorting occurred in or beyond the trans Golgi apparatus. The abnormal sorting of the Od IL-2 receptor is compared with the O-glycosylation dependence of the surface expression and stability of the low-density lipoprotein receptor, decay-accelerating factor, and the major antigen envelope protein of Epstein-Barr virus.

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Pogue, S. L., e C. C. Goodnow. "Ig heavy chain extracellular spacer confers unique glycosylation of the Mb-1 component of the B cell antigen receptor complex." Journal of Immunology 152, n.º 8 (15 de abril de 1994): 3925–34. http://dx.doi.org/10.4049/jimmunol.152.8.3925.

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Abstract A unique functional role for the B cell Ag receptor, IgD, has not yet been identified. A number of properties of IgD, such as distinct intron-exon organization and a conserved pattern of developmental expression, suggest a selective evolutionary advantage for this receptor isotype. To explore structural features of IgD that may confer unique functions, chimeric Ag receptors were generated in which small segments of the IgD heavy chain membrane proximal regions were substituted for corresponding segments of the IgM heavy chain. Polypeptides that associate with the Ig receptors were analyzed. Mb-1/Ig-alpha, a signal transduction molecule, is known to be glycosylated in a distinct manner when associated with IgD compared to when associated with other isotypes. We report that this differential glycosylation results because one N-linked carbohydrate on Mb-1 fails to be processed into an Endo-H-resistant form when associated with IgM or IgG, whereas both N-linked carbohydrates are processed on Mb-1 associated with IgD. By preparing chimeric IgM-IgD heavy chains, substitution of the IgD extracellular spacer segment alone was found to be necessary and sufficient to confer an IgD-type glycosylation pattern on the Mb-1 molecule. This altered glycosylation pattern, however, did not confer a detectable difference in calcium mobilization or in protein tyrosine phosphorylation upon receptor stimulation. Interestingly, a similar altered glycosylation pattern has been reported for the T cell Ag receptor complex in which carbohydrates on the CD3 delta-chain are fully processed in gamma delta-T cell receptors but only partially processed in alpha beta-T cell receptors.

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Pathak, R. K., R. K. Merkle, R. D. Cummings, J. L. Goldstein, M. S. Brown e R. G. Anderson. "Immunocytochemical localization of mutant low density lipoprotein receptors that fail to reach the Golgi complex." Journal of Cell Biology 106, n.º 6 (1 de junho de 1988): 1831–41. http://dx.doi.org/10.1083/jcb.106.6.1831.

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In the low density lipoprotein (LDL) receptor system, blocks in intracellular movement of a cell surface receptor result from naturally occurring mutations. These mutations occur in patients with familial hypercholesterolemia. One class of mutant LDL receptor genes (class 2 mutations) produces a receptor that is synthesized and glycosylated in the endoplasmic reticulum (ER) but does not reach the cell surface. These receptors contain serine/threonine-linked (O-linked) carbohydrate chains with core N-acetylgalactosamine residues and asparagine-linked (N-linked) carbohydrate chains of the high mannose type that are only partially trimmed. To determine the site of blockage in transport, we used electron microscope immunohistochemistry to compare the intracellular location of LDL receptors in normal human fibroblasts with their location in class 2 mutant fibroblasts. In normal cells, LDL receptors were located in coated pits, coated vesicles, endosomes, multivesicular bodies, and portions of the Golgi complex. In contrast, the mutant receptors in class 2 cells were almost entirely confined to rough ER and irregular extensions of the rough ER. Metabolic labeling studies with [3H]glucosamine confirmed that these mutant receptors contain core O-linked sugars, suggesting that the enzymes that attach these residues are located in the rough ER or the transitional zone of the ER. These studies establish that naturally occurring mutations in cell surface receptors can cause the receptors to remain trapped in the ER, thereby preventing their normal function and producing a genetic disease.

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Tan, Ming, e Xi Jiang. "Norovirus Gastroenteritis, Carbohydrate Receptors, and Animal Models". PLoS Pathogens 6, n.º 8 (26 de agosto de 2010): e1000983. http://dx.doi.org/10.1371/journal.ppat.1000983.

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Linnartz, Bettina, Liviu-Gabriel Bodea e Harald Neumann. "Microglial carbohydrate-binding receptors for neural repair". Cell and Tissue Research 349, n.º 1 (14 de fevereiro de 2012): 215–27. http://dx.doi.org/10.1007/s00441-012-1342-7.

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BONAR-LAW, R. P., A. P. DAVIS e B. A. MURRAY. "ChemInform Abstract: Artificial Receptors for Carbohydrate Derivatives." ChemInform 22, n.º 10 (23 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199110299.

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Grange, Philippe A., Alan K. Erickson, Timothy J. Anderson e David H. Francis. "Characterization of the Carbohydrate Moiety of Intestinal Mucin-Type Sialoglycoprotein Receptors for the K88ac Fimbrial Adhesin of Escherichia coli". Infection and Immunity 66, n.º 4 (1 de abril de 1998): 1613–21. http://dx.doi.org/10.1128/iai.66.4.1613-1621.1998.

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ABSTRACT We have previously identified two mucin-type sialoglycoproteins from porcine intestinal epithelial cells with approximate molecular masses of 210 (intestinal mucin-type glycoprotein IMTGP-1) and 240 kDa (IMTGP-2) as receptors for the K88ab and K88ac fimbrial adhesins ofEscherichia coli. These receptors are detected in intestinal brush border membrane preparations from pigs with adhesive phenotypes but not from pigs with nonadhesive phenotypes and are postulated to be important determinants of the susceptibility of pigs to K88ab+ and K88ac+ enterotoxigenic E. coli infections. Using exoglycosidase digestion studies, we have now determined that β-linked galactose is an important component in the recognition of IMTGP-1 and IMTGP-2 by the K88ac adhesin. In addition, we observed a differential distribution of the K88ac adhesin binding activity of IMTGP-1 and IMTGP-2 along the crypt-villus axis, suggesting that receptor activity is dependent on the maturation state of the intestinal epithelial cells. Brush borders from immature intestinal epithelial cells possessed the highest concentrations of IMTGP-1 and IMTGP-2 receptor activity, with a progressive decrease in receptor activity as the cells mature. To characterize the differences in the carbohydrate moieties of IMTGP-1 and IMTGP-2, we developed a procedure for purifying the receptors, using phenol extraction followed by serial lectin affinity chromatography. Carbohydrate compositional analysis of the purified receptors indicated that the carbohydrate moieties of IMTGP-1 and IMTGP-2 consist of both N- and O-glycans containing galactose, glucose, sialic acid, mannose,N-acetylgalactosamine, N-acetylglucosamine, and fucose. The major difference between the two receptors is that IMTGP-2 contains a higher percentage of monosaccharides (mannose and glucose) commonly found in N-glycans.

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Lee, Y. K., e K. Y. Puong. "Competition for adhesion between probiotics and human gastrointestinal pathogens in the presence of carbohydrate". British Journal of Nutrition 88, S1 (setembro de 2002): S101—S108. http://dx.doi.org/10.1079/bjn2002635.

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The adhesion ofLactobacillus rhamnosusGG to human enterocyte-like Caco-2 cells was not inhibited by eight carbohydrates tested, namelyN-acetyl-glucosamine, galactose, glucose, fructose, fucose, mannose, methyl-α-D-mannopyranoside and sucrose. The degree of hydrophobicity predicted the adhesion ofL. rhamnosusGG to Caco-2 cells.L. rhamnosusGG, however, was able to compete withEscherichia coliandSalmonellaspp. of low hydrophobicity and high adhesin–receptor interaction for adhesion to Caco-2 cells. The interference of adhesion of these gastrointestinal (GI) bacteria byL. rhamnosusGG was probably through steric hindrance, and the degree of inhibition was related to the distribution of the adhesin receptors and hydrophobins on the Caco-2 surface. A Carbohydrate Index for Adhesion (CIA) was used to depict the binding property of adhesins on bacteria surfaces. CIA was defined as the sum of the fraction of adhesion in the presence of carbohydrates, with reference to the adhesion measured in the absence of any carbohydrate. The degree of competition for receptor sites betweenLactobacillus caseiShirota and GI bacteria is a function of their CIA distance. There were at least two types of adhesins on the surface ofL. caseiShirota. The study provides a scientific basis for the screening and selection of probiotics that compete with selective groups of pathogens for adhesion to intestinal surfaces. It also provides a model for the characterisation of adhesins and adhesin–receptor interactions.

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Tempel, D. L., e S. F. Leibowitz. "Glucocorticoid receptors in PVN: interactions with NE, NPY, and Gal in relation to feeding". American Journal of Physiology-Endocrinology and Metabolism 265, n.º 5 (1 de novembro de 1993): E794—E800. http://dx.doi.org/10.1152/ajpendo.1993.265.5.e794.

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Norepinephrine (NE) and neuropeptide Y (NPY) potentiate carbohydrate ingestion after injection into the paraventricular nucleus (PVN), whereas injection of galanin (Gal) potentiates fat intake. The present study examines the relation between these neurochemically induced feeding behaviors and the adrenal steroids acting locally within the PVN. Results demonstrate that PVN NE- and NPY-induced carbohydrate intake is abolished by adrenalectomy surgery (ADX) and by local PVN implants of the type II receptor antagonist RU-486. Carbohydrate intake in response to PVN NE or NPY injection is unaffected by the type I antagonist RU-28318. In contrast, the stimulatory effect of PVN Gal injection on fat intake is unchanged by surgical ADX or by PVN administration of RU-486 or RU-28318, suggesting that the stimulatory action of Gal on fat ingestion occurs independently of corticosterone (Cort) and of PVN type I or type II steroid receptors. It is concluded that endogenous Cort has a permissive effect on the carbohydrate feeding responses elicited by NE and NPY in the PVN and that this interaction is mediated by type II glucocorticoid receptors within this nucleus.

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Rauschenberg, Melanie, Eva-Corrina Fritz, Christian Schulz, Tobias Kaufmann e Bart Jan Ravoo. "Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin". Beilstein Journal of Organic Chemistry 10 (16 de junho de 2014): 1354–64. http://dx.doi.org/10.3762/bjoc.10.138.

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The molecular recognition of carbohydrates and proteins mediates a wide range of physiological processes and the development of synthetic carbohydrate receptors (“synthetic lectins”) constitutes a key advance in biomedical technology. In this article we report a synthetic lectin that selectively binds to carbohydrates immobilized in a molecular monolayer. Inspired by our previous work, we prepared a fluorescently labeled synthetic lectin consisting of a cyclic dimer of the tripeptide Cys-His-Cys, which forms spontaneously by air oxidation of the monomer. Amine-tethered derivatives of N-acetylneuraminic acid (NANA), β-D-galactose, β-D-glucose and α-D-mannose were microcontact printed on epoxide-terminated self-assembled monolayers. Successive prints resulted in simple microarrays of two carbohydrates. The selectivity of the synthetic lectin was investigated by incubation on the immobilized carbohydrates. Selective binding of the synthetic lectin to immobilized NANA and β-D-galactose was observed by fluorescence microscopy. The selectivity and affinity of the synthetic lectin was screened in competition experiments. In addition, the carbohydrate binding of the synthetic lectin was compared with the carbohydrate binding of the lectins concanavalin A and peanut agglutinin. It was found that the printed carbohydrates retain their characteristic selectivity towards the synthetic and natural lectins and that the recognition of synthetic and natural lectins is strictly orthogonal.

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Yednock, T. A., E. C. Butcher, L. M. Stoolman e S. D. Rosen. "Receptors involved in lymphocyte homing: relationship between a carbohydrate-binding receptor and the MEL-14 antigen." Journal of Cell Biology 104, n.º 3 (1 de março de 1987): 725–31. http://dx.doi.org/10.1083/jcb.104.3.725.

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Blood-borne lymphocytes extravasate in large numbers within peripheral lymph nodes (PN) and other secondary lymphoid organs. It has been proposed that the initiation of extravasation is based upon a family of cell adhesion molecules (homing receptors) that mediate lymphocyte attachment to specialized high endothelial venules (HEV) within the lymphoid tissues. A putative homing receptor has been identified by the monoclonal antibody, MEL-14, which recognizes an 80-90-kD glycoprotein on the surface of mouse lymphocytes and blocks the attachment of lymphocytes to PN HEV. In a companion study we characterize a carbohydrate-binding receptor on the surface of mouse lymphocytes that also appears to be involved in the interaction of lymphocytes with PN HEV. This receptor selectively binds to fluorescent beads derivatized with PPME, a polysaccharide rich in mannose-6-phosphate. In this report we examine the relationship between this carbohydrate-binding receptor and the putative homing receptor identified by the MEL-14 antibody. We found that: MEL-14 completely and selectively blocks the activity of the carbohydrate-binding receptor on mouse lymphocytes; the ability of six lymphoma cell lines to bind PPME beads correlates with cell-surface expression of the MEL-14 antigen, as well as PN HEV-binding activity; selection of lymphoma cell line variants for PPME-bead binding by fluorescence-activated cell sorting (FACS) produces highly correlated (r = 0.974, P less than 0.001) and selective changes in MEL-14 antigen expression. These results show that the carbohydrate-binding receptor on lymphocytes and the MEL-14 antigen, which have been independently implicated as receptors involved in PN-specific HEV attachment, are very closely related, if not identical, molecules.

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Hoober, J. Kenneth. "ASGR1 and Its Enigmatic Relative, CLEC10A". International Journal of Molecular Sciences 21, n.º 14 (8 de julho de 2020): 4818. http://dx.doi.org/10.3390/ijms21144818.

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The large family of C-type lectin (CLEC) receptors comprises carbohydrate-binding proteins that require Ca2+ to bind a ligand. The prototypic receptor is the asialoglycoprotein receptor-1 (ASGR1, CLEC4H1) that is expressed primarily by hepatocytes. The early work on ASGR1, which is highly specific for N-acetylgalactosamine (GalNAc), established the foundation for understanding the overall function of CLEC receptors. Cells of the immune system generally express more than one CLEC receptor that serve diverse functions such as pathogen-recognition, initiation of cellular signaling, cellular adhesion, glycoprotein turnover, inflammation and immune responses. The receptor CLEC10A (C-type lectin domain family 10 member A, CD301; also called the macrophage galactose-type lectin, MGL) contains a carbohydrate-recognition domain (CRD) that is homologous to the CRD of ASGR1, and thus, is also specific for GalNAc. CLEC10A is most highly expressed on immature DCs, monocyte-derived DCs, and alternatively activated macrophages (subtype M2a) as well as oocytes and progenitor cells at several stages of embryonic development. This receptor is involved in initiation of TH1, TH2, and TH17 immune responses and induction of tolerance in naïve T cells. Ligand-mediated endocytosis of CLEC receptors initiates a Ca2+ signal that interestingly has different outcomes depending on ligand properties, concentration, and frequency of administration. This review summarizes studies that have been carried out on these receptors.

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Magnusson, S., I. Faerevik e T. Berg. "Characterization of retroendocytosis in rat liver parenchymal cells and sinusoidal endothelial cells". Biochemical Journal 287, n.º 1 (1 de outubro de 1992): 241–46. http://dx.doi.org/10.1042/bj2870241.

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After receptor-mediated endocytosis, internalized ligands may be recycled to the cell surface instead of being routed to lysosomes for degradation, a process termed retroendocytosis. We have investigated the kinetics and extent of retroendocytosis of neoglycoproteins after internalization via two carbohydrate-specific receptors in rat liver cells: galactose receptors in parenchymal cells (PC) and mannose receptors in sinusoidal endothelial cells (EC). Retroendocytosis in both cell types occurred with first-order kinetics, and the rate of recycling of internalized ligands was about 4 times higher in EC than in PC. As the length of the internalization pulse was increased, the extent of subsequent retroendocytosis decreased, indicating that retroendocytosis takes place from a relatively early stage in the endocytic pathway. Furthermore, as the degree of carbohydrate substitution of the neoglycoprotein ligands increased, the affinities of the receptors for the ligands and the extent of ligand retroendocytosis increased. In the EC, the relationship between degree of substitution and extent of retroendocytosis was not immediately apparent, as some of the neoglycoprotein ligands used may also bind to and be internalized by scavenger receptors on the EC, causing a decreased apparent retroendocytosis. However, when this interaction was inhibited, this relationship was restored. We conclude that retroendocytosis mainly occurs because of incomplete dissociation of ligands from receptors before receptor recycling to the cell surface and that the affinities of a receptor for its ligand at the cell surface and in the endosomal environment are major factors in determining the extent of retroendocytosis.

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Ströh, Luisa J., Melissa S. Maginnis, Bärbel S. Blaum, Christian D. S. Nelson, Ursula Neu, Gretchen V. Gee, Bethany A. O'Hara et al. "The Greater Affinity of JC Polyomavirus Capsid for α2,6-Linked Lactoseries Tetrasaccharide c than for Other Sialylated Glycans Is a Major Determinant of Infectivity". Journal of Virology 89, n.º 12 (8 de abril de 2015): 6364–75. http://dx.doi.org/10.1128/jvi.00489-15.

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ABSTRACTThe human JC polyomavirus (JCPyV) establishes an asymptomatic, persistent infection in the kidneys of the majority of the population and is the causative agent of the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML) in immunosuppressed individuals. The Mad-1 strain of JCPyV, a brain isolate, was shown earlier to require α2,6-linked sialic acid on the lactoseries tetrasaccharide c (LSTc) glycan for attachment to host cells. In contrast, a JCPyV kidney isolate type 3 strain, WT3, has been reported to interact with sialic acid-containing gangliosides, but the role of these glycans in JCPyV infection has remained unclear. To help rationalize these findings and probe the effects of strain-specific differences on receptor binding, we performed a comprehensive analysis of the glycan receptor specificities of these two representative JCPyV strains using high-resolution X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy, and correlated these data with the results of infectivity assays. We show here that capsid proteins of Mad-1 and WT3 JCPyV can both engage LSTc as well as multiple sialylated gangliosides. However, the binding affinities exhibit subtle differences, with the highest affinity observed for LSTc. Engagement of LSTc is a prerequisite for functional receptor engagement, while the more weakly binding gangliosides are not required for productive infection. Our findings highlight the complexity of virus-carbohydrate interactions and demonstrate that subtle differences in binding affinities, rather than the binding event alone, help determine tissue tropism and viral pathogenesis.IMPORTANCEViral infection is initiated by attachment to receptors on host cells, and this event plays an important role in viral disease. We investigated the receptor-binding properties of human JC polyomavirus (JCPyV), a virus that resides in the kidneys of the majority of the population and can cause the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML) in the brains of immunosuppressed individuals. JCPyV has been reported to interact with multiple carbohydrate receptors, and we sought to clarify how the interactions between JCPyV and cellular carbohydrate receptors influenced infection. Here we demonstrate that JCPyV can engage numerous sialylated carbohydrate receptors. However, the virus displays preferential binding to LSTc, and only LSTc mediates a productive infection. Our findings demonstrate that subtle differences in binding affinity, rather than receptor engagement alone, are a key determinant of viral infection.

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Schmidt, Stephan, Hanqing Wang, Daniel Pussak, Simone Mosca e Laura Hartmann. "Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces". Beilstein Journal of Organic Chemistry 11 (12 de maio de 2015): 720–29. http://dx.doi.org/10.3762/bjoc.11.82.

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Many biological functions at cell level are mediated by the glycocalyx, a dense carbohydrate-presenting layer. In this layer specific interactions between carbohydrate ligands and protein receptors are formed to control cell–cell recognition, cell adhesion and related processes. The aim of this work is to shed light on the principles of complex formation between surface anchored carbohydrates and receptor surfaces by measuring the specific adhesion between surface bound mannose on a concanavalin A (ConA) layer via poly(ethylene glycol)-(PEG)-based soft colloidal probes (SCPs). Special emphasis is on the dependence of multivalent presentation and density of carbohydrate units on specific adhesion. Consequently, we first present a synthetic strategy that allows for controlled density variation of functional groups on the PEG scaffold using unsaturated carboxylic acids (crotonic acid, acrylic acid, methacrylic acid) as grafting units for mannose conjugation. We showed by a range of analytic techniques (ATR–FTIR, Raman microscopy, zeta potential and titration) that this synthetic strategy allows for straightforward variation in grafting density and grafting length enabling the controlled presentation of mannose units on the PEG network. Finally we determined the specific adhesion of PEG-network-conjugated mannose units on ConA surfaces as a function of density and grafting type. Remarkably, the results indicated the absence of a molecular-level enhancement of mannose/ConA interaction due to chelate- or subsite-binding. The results seem to support the fact that weak carbohydrate interactions at mechanically flexible interfaces hardly undergo multivalent binding but are simply mediated by the high number of ligand–receptor interactions.

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Snyder, Greg A., Jennifer Ford, Parizad Torabi-Parizi, James A. Arthos, Peter Schuck, Marco Colonna e Peter D. Sun. "Characterization of DC-SIGN/R Interaction with Human Immunodeficiency Virus Type 1 gp120 and ICAM Molecules Favors the Receptor's Role as an Antigen-Capturing Rather than an Adhesion Receptor". Journal of Virology 79, n.º 8 (15 de abril de 2005): 4589–98. http://dx.doi.org/10.1128/jvi.79.8.4589-4598.2005.

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ABSTRACT The dendritic cell (DC)-specific intercellular adhesion molecule 3 (ICAM-3)-grabbing nonintegrin binding receptor (DC-SIGN) was shown to bind human immunodeficiency virus type 1 (HIV-1) viral envelope protein gp120 and proposed to function as a Trojan horse to enhance trans-virus infection to host T cells. To better understand the mechanism by which DC-SIGN and DC-SIGNR selectively bind HIV-1 gp120, we constructed a series of deletion mutations in the repeat regions of both receptors. Different truncated receptors exist in different oligomeric forms. The carbohydrate binding domain without any repeats was monomeric, whereas the full extracellular receptors existed as tetramers. All reconstituted receptors retained their ability to bind gp120. The dissociation constant, however, differed drastically from micromolar values for the monomeric receptors to nanomolar values for the tetrameric receptors, suggesting that the repeat region of these receptors contributes to the avidity of gp120 binding. Such oligomerization may provide a mechanism for the receptor to selectively recognize pathogens containing multiple high-mannose-concentration carbohydrates. In contrast, the receptors bound to ICAMs with submicromolar affinities that are similar to those of two nonspecific cell surface glycoproteins, FcγRIIb and FcγRIII, and the oligomerization of DC-SIGNR resulted in no increase in binding affinity to ICAM-3. These findings suggest that DC-SIGN may not discriminate other cell surface glycoproteins from ICAM-3 binding. The pH dependence in DC-SIGN binding to gp120 showed that the receptor retained high-affinity gp120 binding at neutral pH but lost gp120 binding at pH 5, suggesting a release mechanism of HIV in the acidic endosomal compartment by DC-SIGN. Our work contradicts the function of DC-SIGN as a Trojan horse to facilitate HIV-1 infection; rather, it supports the function of DC-SIGN/R (a designation referring to both DC-SIGN and DC-SIGNR) as an antigen-capturing receptor.

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Kim, Jung-Ja P., Linda J. Olson e Nancy M. Dahms. "Carbohydrate recognition by the mannose-6-phosphate receptors". Current Opinion in Structural Biology 19, n.º 5 (outubro de 2009): 534–42. http://dx.doi.org/10.1016/j.sbi.2009.09.002.

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Mazik, Monika, Matthias Kuschel e Willi Sicking. "Crown Ethers as Building Blocks for Carbohydrate Receptors". Organic Letters 8, n.º 5 (março de 2006): 855–58. http://dx.doi.org/10.1021/ol052902g.

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Yang, Xiaochuan, Yunfeng Cheng e Binghe Wang. "ChemInform Abstract: Synthetic Lectin Mimics Artificial Carbohydrate Receptors". ChemInform 43, n.º 18 (5 de abril de 2012): no. http://dx.doi.org/10.1002/chin.201218244.

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Welti, Roger, e François Diederich. "A New Family of C3-Symmetrical Carbohydrate Receptors". Helvetica Chimica Acta 86, n.º 2 (fevereiro de 2003): 494–503. http://dx.doi.org/10.1002/hlca.200390049.

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Sehadova, Hana, Yoko Takasu, Anna Zaloudikova, Yu-Hsien Lin, Ivo Sauman, Hideki Sezutsu, Lenka Rouhova, Dalibor Kodrik e Michal Zurovec. "Functional Analysis of Adipokinetic Hormone Signaling in Bombyx mori". Cells 9, n.º 12 (11 de dezembro de 2020): 2667. http://dx.doi.org/10.3390/cells9122667.

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Insect adipokinetic hormones (AKHs) are short peptides produced in the corpora cardiaca and are responsible for mobilizing energy stores from the fat body to the hemolymph. Three related peptides, AKH1, AKH2, and AKH/corazonin-related peptide (ACP) as well as three AKH receptors have been reported in Bombyx mori. AKH1 and AKH2 are specific for the AKHR1 receptor, whereas ACP interacts with the other two AKHRs. To assess the effect of the two silkworm AKHs and ACP in the regulation of energy homeostasis we examined the expression pattern of the three peptides and their receptors as well as their effect on the level of carbohydrates and lipids in the hemolymph. Our results support the hypothesis that only AKH1 and AKH2 peptides together with the AKHR1 receptor are involved in the maintenance of energy homeostasis. Because Bombyx AKHR1 (BmAKHR1) seems to be a true AKHR we generated its mutation. The BmAKHR1 mutant larvae display significantly lower carbohydrate and lipid levels in the hemolymph and reduced sensitivity to starvation. Our study clarifies the role of BmAKHR1 in energy homeostasis.

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Raposo, Cláudia D., André B. Canelas e M. Teresa Barros. "Human Lectins, Their Carbohydrate Affinities and Where to Find Them". Biomolecules 11, n.º 2 (29 de janeiro de 2021): 188. http://dx.doi.org/10.3390/biom11020188.

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Lectins are a class of proteins responsible for several biological roles such as cell-cell interactions, signaling pathways, and several innate immune responses against pathogens. Since lectins are able to bind to carbohydrates, they can be a viable target for targeted drug delivery systems. In fact, several lectins were approved by Food and Drug Administration for that purpose. Information about specific carbohydrate recognition by lectin receptors was gathered herein, plus the specific organs where those lectins can be found within the human body.

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Leibiger, Betty, Manuel Stapf e Monika Mazik. "Cycloalkyl Groups as Building Blocks of Artificial Carbohydrate Receptors: Studies with Macrocycles Bearing Flexible Side-Arms". Molecules 27, n.º 21 (7 de novembro de 2022): 7630. http://dx.doi.org/10.3390/molecules27217630.

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The cyclopentyl group was expected to act as a building block for artificial carbohydrate receptors and to participate in van der Waals contacts with the carbohydrate substrate in a similar way as observed for the pyrrolidine ring of proline in the crystal structures of protein-carbohydrate complexes. Systematic binding studies with a series of 1,3,5-trisubstituted 2,4,6-triethylbenzenes bearing various cycloalkyl groups as recognition units provided indications of the involvement of these groups in the complexation process and showed the influence of the ring size on the receptor efficiency. Representatives of compounds that exhibit a macrocyclic backbone and flexible side arms were now chosen as further model systems to investigate whether the previously observed effects represent a general trend. Binding studies with these macrocycles towards β-D-glucopyranoside, an all-equatorial substituted carbohydrate substrate, included 1H NMR spectroscopic titrations and microcalorimetric investigations. The performed studies confirmed the previously observed tendency and showed that the compound bearing cyclohexyl groups displays the best binding properties.

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Bezouška, Karel. "Carbohydrate and Non-Carbohydrate Ligands for the C-Type Lectin-Like Receptors of Natural Killer Cells. A Review". Collection of Czechoslovak Chemical Communications 69, n.º 3 (2004): 535–63. http://dx.doi.org/10.1135/cccc20040535.

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The superfamily of C-type animal lectins is defined by a sequence motif of the carbohydrate- recognition domains (CRDs) and comprises seven groups of molecules. The soluble proteins are group I proteoglycans, group III collectins, and group VII containing the isolated CRDs. Type I membrane proteins include group IV selectins and group VI macrophage receptors and related molecules. Type II membrane proteins are group II hepatic lectins and group V natural killer cell receptors. The latter group has recently attracted considerable attention of the biomedical community. These receptors are arranged at the surface of lymphocytes as homo- or heterodimers composed of two polypeptides consisting of N-terminal peptide tails responsible for signaling, transmembrane domain, neck regions of varying length, and C-terminal lectin-like domains (CTLDs). Since this group is evolutionarily most distant from the rest of C-type animal lectins, the sequence of the C-terminal ligand-binding domain has diversified to accommodate other ligands than calcium or carbohydrates. These domains are referred to as natural killer domains (NKDs) forming a large percentage of CTLDs in vertebrates. Here are summarized the data indicating that calcium, carbohydrates, peptides, and large proteins such as major histocompatibility complex (MHC) class I can all be ligands for NKDs. The wide range of ligands that can be recognized by NKDs includes some new, unexpected compounds such as signal peptide-derived fragments, heat shock proteins, or oxidized lipids. The biological importance of this extended range of recognition abilities is also discussed. A review with 134 references.

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Cacciarini, Martina, Cristina Nativi, Martina Norcini, Samuele Staderini, Oscar Francesconi e Stefano Roelens. "Pyrrolic tripodal receptors for carbohydrates. Role of functional groups and binding geometry on carbohydrate recognition". Org. Biomol. Chem. 9, n.º 4 (2011): 1085–91. http://dx.doi.org/10.1039/c0ob00651c.

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Striegler, Susanne. "Selective Carbohydrate Recognition by Synthetic Receptors in Aqueous Solution". Current Organic Chemistry 7, n.º 1 (1 de janeiro de 2003): 81–102. http://dx.doi.org/10.2174/1385272033373201.

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Takamatsu, Hiroyuki, Yoshihiro Nakata e Tomio Segawa. "Characterization of the carbohydrate chain on substance P receptors." Japanese Journal of Pharmacology 55 (1991): 114. http://dx.doi.org/10.1016/s0021-5198(19)38352-0.

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Mazik, Monika, e Andrè Hartmann. "Phenanthroline Unit as a Building Block for Carbohydrate Receptors". Journal of Organic Chemistry 73, n.º 19 (3 de outubro de 2008): 7444–50. http://dx.doi.org/10.1021/jo8005842.

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Lepenies, Bernd, Junghoon Lee e Sanjiv Sonkaria. "Targeting C-type lectin receptors with multivalent carbohydrate ligands". Advanced Drug Delivery Reviews 65, n.º 9 (agosto de 2013): 1271–81. http://dx.doi.org/10.1016/j.addr.2013.05.007.

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Bravo, M. Fernando, Kalanidhi Palanichamy, Milan A. Shlain, Frank Schiro, Yasir Naeem, Mateusz Marianski e Adam B. Braunschweig. "Synthesis and Binding of Mannose‐Specific Synthetic Carbohydrate Receptors". Chemistry – A European Journal 26, n.º 51 (17 de agosto de 2020): 11782–95. http://dx.doi.org/10.1002/chem.202000481.

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Stang, E., N. Roos, M. Schlüter, T. Berg e J. Krause. "Evidence for carbohydrate-independent endocytosis of tissue-type plasminogen activator by liver cells". Biochemical Journal 285, n.º 3 (1 de agosto de 1992): 799–804. http://dx.doi.org/10.1042/bj2850799.

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In the liver, tissue-type plasminogen activator (t-PA) is endocytosed by hepatic parenchymal (PC), endothelial (EC) and Kupffer (KC) cells. Although the endocytosis is receptor-mediated, it remains a matter of discussion which receptors are involved in this catabolic process. To evaluate the role of a protein-specific receptor, as well as the possible involvement of the galactose receptor on PC and the mannose receptor on EC, we have employed different glycosylation variants of t-PA in biochemical and immunocytochemical studies. Partial or total removal of carbohydrate side-chains by endoglycosidases did not prevent clearance and hepatic endocytosis of t-PA by either of the liver cell types. Blockade of the galactose and mannose receptors by co-application of a large excess of the glycoprotein ovalbumin remained without effect on the binding and uptake of t-PA by hepatic cells. However, the contribution of different liver cell types to the hepatic clearance of t-PA was to a certain extent dependent on the type of oligosaccharide chains removed. The mannose receptor on EC is partially responsible for the clearance of t-PA by this cell type, whereas the galactose receptor does not seem to be involved in this process. The results obtained in this study further demonstrate that the major portion of the hepatic catabolism of t-PA is independent of its carbohydrate side-chains.

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Pavlíček, J., D. Kavan, P. Pompach, P. Novák, O. Lukšan e K. Bezouška. "Lymphocyte activation receptors: new structural paradigms in group V of C-type animal lectins". Biochemical Society Transactions 32, n.º 6 (26 de outubro de 2004): 1124–26. http://dx.doi.org/10.1042/bst0321124.

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The structure–function relationship in group V of C-type animal lectins remains incompletely understood despite the new structures of NK (natural killer) cell receptors that have been solved recently. Recombinant, soluble forms of rat and human NKR-P1 and CD69 that we obtained after in vitro refolding were analysed by Fourier transform–ion cyclotron resonance MS and heteronuclear NMR (1H-15N correlation). In NKR-P1, calcium may not be removed by chelating agents because of the very high affinity of binding. In CD69, incorporation of calcium causes a structural shift in several amino acids important for the interaction with carbohydrates. Structural studies have also allowed us to understand an interesting preference of these receptors for either linear (NKR-P1) or branched (CD69) carbohydrate sequences.

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Rodrigues Mantuano, Natalia, Marina Natoli, Alfred Zippelius e Heinz Läubli. "Tumor-associated carbohydrates and immunomodulatory lectins as targets for cancer immunotherapy". Journal for ImmunoTherapy of Cancer 8, n.º 2 (outubro de 2020): e001222. http://dx.doi.org/10.1136/jitc-2020-001222.

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During oncogenesis, tumor cells present specific carbohydrate chains that are new targets for cancer immunotherapy. Whereas these tumor-associated carbohydrates (TACA) can be targeted with antibodies and vaccination approaches, TACA including sialic acid-containing glycans are able to inhibit anticancer immune responses by engagement of immune receptors on leukocytes. A family of immune-modulating receptors are sialic acid-binding Siglec receptors that have been recently described to inhibit antitumor activity mediated by myeloid cells, natural killer cells and T cells. Other TACA-binding receptors including selectins have been linked to cancer progression. Recent studies have shown that glycan-lectin interactions can be targeted to improve cancer immunotherapy. For example, interactions between the immune checkpoint T cell immunoglobulin and mucin-domain containing-3 and the lectin galectin-9 are targeted in clinical trials. In addition, an antibody against the lectin Siglec-15 is being tested in an early clinical trial. In this review, we summarize the previous and current efforts to target TACA and to inhibit inhibitory immune receptors binding to TACA including the Siglec-sialoglycan axis.

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Napper, Catherine E., Kurt Drickamer e Maureen E. Taylor. "Collagen binding by the mannose receptor mediated through the fibronectin type II domain". Biochemical Journal 395, n.º 3 (11 de abril de 2006): 579–86. http://dx.doi.org/10.1042/bj20052027.

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The macrophage mannose receptor is the prototype for a family of receptors each having an extracellular region consisting of an N-terminal cysteine-rich domain related to the R-type carbohydrate-recognition domain of ricin, a fibronectin type II domain and eight to ten domains related to C-type carbohydrate-recognition domains. The mannose receptor acts as a molecular scavenger, clearing harmful glycoconjugates or micro-organisms through recognition of their defining carbohydrate structures. Cell-adhesion assays, as well as collagen-binding assays, have now been used to show that the mannose receptor can also bind collagen and that the fibronectin type II domain mediates this activity. Neither of the two types of sugar-binding domain in the receptor is involved in collagen binding. Fibroblasts expressing the mannose receptor adhere to type I, type III and type IV collagens, but not to type V collagen, and the adherence is inhibited by isolated mannose receptor fibronectin type II domain. The fibronectin type II domain shows the same specificity for collagen as the whole receptor, binding to type I, type III and type IV collagens. This is the first activity assigned to the fibronectin type II domain of the mannose receptor. The results suggest additional roles for this multifunctional receptor in mediating collagen clearance or cell–matrix adhesion.

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MCABEE, Douglas D., Xin JIANG e Kevin B. WALSH. "Lactoferrin binding to the rat asialoglycoprotein receptor requires the receptor's lectin properties". Biochemical Journal 348, n.º 1 (9 de maio de 2000): 113–17. http://dx.doi.org/10.1042/bj3480113.

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Lactoferrin binds to rat hepatic lectin 1 (RHL1), the major subunit of the asialoglycoprotein (ASGP) receptor, with high affinity, by a galactose-independent mechanism. To better understand the molecular basis of this novel interaction, we compared the binding of lactoferrin and asialo-orosomucoid (ASOR) to isolated rat hepatocytes and to purified ASGP receptors as a function of pH, Ca2+ and receptor acylation. Binding of 125I-lactoferrin and 125I-ASOR to isolated rat hepatocytes at 4 °C decreased sharply at pH < 6, following similar titration curves. Binding of 125I-lactoferrin and 125I-ASOR to hepatocytes was Ca2+-dependent. Binding increased progressively at ≥ 300 μM CaCl2, in the presence of 1 mM EDTA. Monensin treatment of hepatocytes, which causes hepatocytes to accumulate inactive ASGP receptors, reduced surface binding of 125I-lactoferrin and 125I-ASOR by 46 and 49%, respectively, with only a 16% loss of immunodetectable receptor protein from the cell surface. Finally, deacylation of purified ASGP receptors in vitro with 1 M hydroxylamine abolished receptor lectin activity as reflected by the loss of 125I-ASOR binding as well as the complete loss of specific 125I-lactoferrin binding. Treatment with 1 M Tris had no effect on binding of either ligand. We conclude from these data that galactose-independent lactoferrin binding to the ASGP receptor requires the receptor's carbohydrate-recognition domain to be in an active configuration. An active configuration is promoted by neutral pH and Ca2+, and also requires the receptor subunits to be acylated.

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Smith, Brenda K., David A. York e George A. Bray. "Activation of hypothalamic serotonin receptors reduced intake of dietary fat and protein but not carbohydrate". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 277, n.º 3 (1 de setembro de 1999): R802—R811. http://dx.doi.org/10.1152/ajpregu.1999.277.3.r802.

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Systemic treatment with dexfenfluramine (dF), fluoxetine, or serotonin (5-hydroxytryptamine, 5-HT) recently was shown to suppress fat and occasionally protein but not carbohydrate intake in rats when a macronutrient selection paradigm was employed. These reports contrast with the prevailing literature, which for the past decade has described a role for serotonin neurotransmission in the modification of dietary carbohydrate consumption. To test the hypothesis that the suppression of fat selection and/or consumption by systemic serotonin agonists involves stimulation of central 5-HT receptors, a series of experiments was performed in nondeprived rats. In experiment 1, third cerebroventricular (3V) infusion of the nonselective 5-HT antagonist metergoline prevented the reduction in fat but not carbohydrate feeding caused by systemic dF. Furthermore, 3V metergoline alone increased fat intake. In experiments 2 and 3, 3V infusion of 5-HT1B/2C receptor agonistsd-norfenfluramine (dNF) or quipazine inhibited fat intake exclusively. Next, the infusion ofdNF or 5-HT into the region of the paraventricular nucleus (PVN) reduced both fat and protein intake ( experiments 4 and 5). Finally, in experiment 6, when rats were grouped by baseline diet preference, 5-HT infused into the PVN led to a dose-related decrease in fat intake in both carbohydrate- and fat-preferring rats. In contrast, there were no dose effects of 5-HT on carbohydrate or protein intake in either preference group. However, in fat-preferring rats, the highest dose of 5-HT reduced intake of all three macronutrient diets. These results demonstrate a selective effect of exogenous serotonergic drugs in the hypothalamus to reduce fat rather than carbohydrate intake and suggest that higher baseline fat intake enhances responsivity to serotonergic drugs.

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