Relevant bibliographies by topics / Receptor affinity

Academic literature on the topic 'Receptor affinity'

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Published: 4 June 2021
Last updated: 19 February 2023

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Journal articles on the topic "Receptor affinity"

1

Bailon, P., and D. V. Weber. "Receptor-affinity chromatography." Nature 335, no. 6193 (October 1988): 839–40. http://dx.doi.org/10.1038/335839a0.

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KOHANSKI, RONALD A., and M. DANIEL LANE. "Receptor Affinity Chromatography." Annals of the New York Academy of Sciences 447, no. 1 Biotin (June 1985): 373–85. http://dx.doi.org/10.1111/j.1749-6632.1985.tb18452.x.

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Dunn, W. A., T. P. Connolly, and A. L. Hubbard. "Receptor-mediated endocytosis of epidermal growth factor by rat hepatocytes: receptor pathway." Journal of Cell Biology 102, no. 1 (January 1, 1986): 24–36. http://dx.doi.org/10.1083/jcb.102.1.24.

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Substantial amounts of epidermal growth factor (EGF) are cleared from the circulation by hepatocytes via receptor-mediated endocytosis and subsequently degraded within lysosomes. We have used a combined biochemical and morphological approach to examine the fate of the receptor after exposure to EGF. Polyclonal antibodies were prepared against the purified receptor and their specificity established by immunoprecipitation and immunoblotting techniques. The EGF receptor was then localized by immunofluorescence and immunoperoxidase techniques and quantified on immunoblots. In untreated livers, EGF receptor was restricted to the sinusoidal and lateral surfaces of hepatocytes. 2-4 min after exposure of cells to EGF, the receptor was found in small vesicles (i.e., coated vesicles) as well as larger vesicles and tubules at the cell periphery. By 15 min the receptor was found in multivesicular endosomes located near bile canaliculi. Exposure of hepatocytes to EGF also resulted in a rapid loss of receptor protein from total liver homogenates and a decrease in its half-life from 8.7 h in control livers to 2.5 h. This EGF-induced loss of receptors was not observed when lysosomal proteinases were inhibited by leupeptin or when endosome/lysosome fusion was prevented by low temperature (16 degrees C). In the presence of leupeptin, receptor could be detected in structures identified as lysosomes using acid-phosphatase cytochemistry. All these results suggested rapid internalization of EGF receptors in response to ligand and degradation within lysosomes. However, four times more ligand was degraded at 8 h than the number of high-affinity (Kd of 8-15 nM) EGF-binding sites lost, suggesting either (a) high-affinity receptors were recycled, and/or (b) more than 300,000 receptors were available for EGF uptake. We identified and characterized a latent pool of approximately 300,000 low-affinity receptors (Kd approximately 200 nM) that could be separated on sucrose gradients from the plasma membrane pool of approximately 300,000 high-affinity receptors (Kd of 8-15 nM). Despite the differences in their binding affinities, the high- and low-affinity receptors appeared to be structurally identical and were both EGF-dependent protein kinases. In addition, the dynamics of the low-affinity receptors were consistent with a functional role in EGF uptake and delivery to lysosomes.
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Feldman, R. D., G. W. Hunninghake, and W. L. McArdle. "Beta-adrenergic-receptor-mediated suppression of interleukin 2 receptors in human lymphocytes." Journal of Immunology 139, no. 10 (November 15, 1987): 3355–59. http://dx.doi.org/10.4049/jimmunol.139.10.3355.

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Abstract Adrenergic receptor agonists are known to attenuate the proliferative response of human lymphocytes after activation; however, their mechanism of action is unknown. Since expression of interleukin 2 (IL-2) receptors is a prerequisite for proliferation, the effect of beta-adrenergic receptor agonists on lymphocyte IL-2 receptors was studied on both mitogen-stimulated lymphocytes and IL-2-dependent T lymphocyte cell lines. In both cell types the beta-adrenergic receptor agonist isoproterenol blocked the expression of IL-2 receptors, as determined with the IL-2 receptor anti-TAC antibody. To determine the effect of beta-adrenergic agonists on expression of the high affinity IL-2 receptors, [125I]IL-2 binding studies were performed at concentrations selective for high affinity sites. No significant effect of beta-adrenergic agonists on high affinity IL-2 receptor sites could be detected. The data demonstrate that beta-adrenergic receptor agonists down-regulate IL-2 receptors primarily affecting low affinity sites.
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Jonas, H. A., and L. C. Harrison. "Disulphide reduction alters the immunoreactivity and increases the affinity of insulin-like growth-factor-I receptors in human placenta." Biochemical Journal 236, no. 2 (June 1, 1986): 417–23. http://dx.doi.org/10.1042/bj2360417.

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We previously identified two forms of the insulin-like growth-factor-I (IGF-I) receptor in human placenta: a lower-affinity form reactive with an autoantiserum (B-2) to the insulin receptor and a higher-affinity non-immunoreactive form [Jonas & Harrison (1985) J. Biol. Chem. 260, 2288-2294]. Evidence is now presented that the lower-affinity immunoreactive forms are convertible into higher-affinity non-immunoreactive forms via reduction of receptor disulphide bonds. Treatment of placental membranes with increasing concentrations of dithiothreitol (DTT): (1) converted native Mr-290 000 heterotetrameric IGF-I receptors into Mr-180 000 dimers (determined by chemical cross-linking of 125I-IGF-I with disuccinimidyl suberate); (2) increased 125I-IGF-I binding, owing to an increase in receptor affinity; and (3) abolished the reactivity of Triton-solubilized IGF-I receptors with antiserum B-2 and transformed the curvilinear plot of IGF-I binding to a linear form. In isolated complexes between receptor and B-2 antibody, DTT increased 125I-IGF-I binding and released a single class of higher affinity IGF-I receptors of Mr 180,000. Thus DTT-treated IGF-I receptors have similar properties to the higher-affinity non-immunoreactive forms of the native receptor, except that reduced dimeric forms are not detected by cross-linking of 125I-IGF-I to native membranes. Cleavage of the inter-dimeric disulphide bonds is therefore not a prerequisite for higher-affinity binding or loss of immunoreactivity. These observations suggest that the thiol redox state of the IGF-I receptor in vivo is an important determinant of receptor conformation and therefore of the biological responses to IGF-I.
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Kristensen, C., A. S. Andersen, M. Hach, F. C. Wiberg, L. Schäffer, and T. Kjeldsen. "A single-chain insulin-like growth factor I/insulin hybrid binds with high affinity to the insulin receptor." Biochemical Journal 305, no. 3 (February 1, 1995): 981–86. http://dx.doi.org/10.1042/bj3050981.

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1. To investigate the structure/function relationship of the interaction between ligand and receptor in the insulin-like growth factor I (IGF-I) and insulin receptor systems we have prepared and characterized a single-chain insulin/IGF-I hybrid. The single-chain hybrid consists of the insulin molecule combined with the C domain of IGF-I. The single-chain hybrid was found to bind with high affinity to both truncated soluble insulin receptors and membrane-bound holoreceptors. The affinity for interacting with the soluble truncated insulin receptors was 55-94% relative to insulin, and affinity for membrane-bound insulin receptors was 113% of that of insulin. Furthermore we found that the affinity of the single-chain hybrid molecule for IGF-I receptors was 19-28% relative to IGF-I. 2. The affinity of the single-chain hybrid for chimeric insulin/IGF-I receptors exceeded that of either natural ligand. This indicates that coordinately changing domains of the receptors and the ligands can induce higher affinity of ligand for receptor, supporting the idea that these receptors have a common ligand-binding site [Kjeldsen, Andersen, Wiberg, Rasmussen, Schäffer, Balschmidt, Møller and Møller (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 4404-4408]. 3. In contrast with what was generally assumed about the ligand structure required for binding to the insulin receptor we demonstrate the first single-chain insulin analogue that can bind with high affinity to the insulin receptor.
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Dormann, Dirk, Ji-Yun Kim, Peter N. Devreotes, and Cornelis J. Weijer. "cAMP receptor affinity controls wave dynamics, geometry and morphogenesis inDictyostelium." Journal of Cell Science 114, no. 13 (July 1, 2001): 2513–23. http://dx.doi.org/10.1242/jcs.114.13.2513.

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Serpentine G-protein-coupled cAMP receptors are key components in the detection and relay of the extracellular cAMP waves that control chemotactic cell movement during Dictyostelium development. During development the cells sequentially express four closely related cAMP receptors of decreasing affinity. In this study, we investigated the effect of cAMP receptor type and affinity on the dynamics of cell-cell signalling in vivo, by measuring the dynamics of wave initiation and propagation in a variety of cAMP receptor mutants. We found that receptor affinity controls the frequency of wave initiation, but it does not determine wave propagation velocity, thus resulting in dramatic changes in wave geometry. In the limiting case, the affinity of the receptor is so low that waves can still be initiated but no stable centres form - thus, the cells cannot aggregate. In mounds, expression of low affinity receptors results in slow concentric waves instead of the normally observed multi-armed spiral waves. Under these conditions there is no rotational cell movement and the hemispherical mounds cannot transform into slugs. These results highlight the importance of receptor number and affinity in the proper control of cell-cell signalling dynamics required for the successful completion of development.
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Bevan, John A., Rosemary D. Bevan, and S. Martin Shreeve. "Variable receptor affinity hypothesis." FASEB Journal 3, no. 6 (April 1989): 1696–704. http://dx.doi.org/10.1096/fasebj.3.6.2564831.

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Yamashina, Masahiro, Takahiro Tsutsui, Yoshihisa Sei, Munetaka Akita, and Michito Yoshizawa. "A polyaromatic receptor with high androgen affinity." Science Advances 5, no. 4 (April 2019): eaav3179. http://dx.doi.org/10.1126/sciadv.aav3179.

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Biological receptors distinguish and bind steroid sex hormones, e.g., androgen-, progestogen-, and estrogen-type hormones, with high selectivity. To date, artificial molecular receptors have been unable to discriminate between these classes of biosubstrates. Here, we report that an artificial polyaromatic receptor preferentially binds a single molecule of androgenic hormones, known as “male” hormones (indicated with m), over progestogens and estrogens, known as “female” hormones (indicated with f), in water. Competitive experiments established the binding selectivity of the synthetic receptor for various sex hormones to be testosterone (m) > androsterone (m) >> progesterone (f) > β-estradiol (f) > pregnenolone (f) > estriol (f). These bindings are driven by the hydrophobic effect, and the observed selectivity arises from multiple CH-π contacts and hydrogen-bonding interactions in the semirigid polyaromatic cavity. Furthermore, micromolar fluorescence detection of androgen was demonstrated using the receptor containing a fluorescent dye in water.
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Broudy, Virginia C., Nancy L. Lin, Diana F. Sabath, Thalia Papayannopoulou, and Kenneth Kaushansky. "Human Platelets Display High-Affinity Receptors for Thrombopoietin." Blood 89, no. 6 (March 15, 1997): 1896–904. http://dx.doi.org/10.1182/blood.v89.6.1896.

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Abstract Thrombopoietin (Tpo) is a major regulator of megakaryopoiesis both in vivo and in vitro. Tpo initiates its biologic effects by binding to the Mpl receptor, which is a member of the hematopoietin receptor family. To define the Tpo binding characteristics of the Mpl receptor, we iodinated purified 70-kD recombinant human Tpo using the Bolton-Hunter reagent. Autoradiographic analysis of 125I-Tpo binding to normal human marrow mononuclear cells showed many grains specifically associated with megakaryocytes; there were no grains specifically associated with myeloblasts or erythroblasts. Equilibrium binding experiments with 125I-Tpo and normal human platelets showed a single class of high-affinity receptors (kd, 190 pmol/L) with approximately 30 Mpl receptors per platelet. Affinity cross-linking with 125I-Tpo showed that the Mpl receptor on platelets is of molecular weight ∼98 kD. Despite their sequence similarity, erythropoietin and Tpo did not cross-compete for binding to BaF3 cells engineered to coexpress Mpl receptor and erythropoietin receptor. Progeny of normal human burst-forming units-erythroid (BFU-E) contained Mpl receptor mRNA, and flow cytometric analysis showed the presence of Mpl receptor protein on the surface of these cells. These data indicate that display of the Mpl receptor is not limited to the megakaryocytic lineage, but also includes progeny of BFU-E. Like receptors for other hematopoietic cytokines, the binding affinity of the Mpl receptor for Tpo is high, with relatively few receptors displayed per cell. These results suggest that the effects of Tpo to speed red blood cell recovery after myelosuppressive therapy in vivo and to enhance colony-forming unit-erythroid generation in vitro may be mediated by direct interaction of Tpo and erythroid progenitor cells.
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Dissertations / Theses on the topic "Receptor affinity"

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Scammells, Peter J., and n/a. "Pyrazolo(3,4-d)Pyrimidines and adenosine receptors: a structure/activity study." Griffith University. Division of Science and Technology, 1990. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050826.141630.

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Pyrazolopyrimidines are a general class of compounds which exhibit Aj adenosine receptor affmity. A number of pyrazolo(3,4-d)pyrimidine analogues of isoguanosine and i-methylisoguanosine has been synthesised. All compounds were tested forAi adenosine receptor affinity using a (311) R-PIA competitive binding assay. The N-i and N-5 positions were substituted with a number of different ailcyl and aryi groups. 3-Chiorophenyl substitution of the N-i position and butyl substitution of the N-5 position greatly enhanced the overall adenosine receptor affinity. Substitution by a methyl group at the N-7 position fixed the C-4 position in the imino tautomeric form. This resulted in a marked reduction in activity. The substitution of the N-2 position with a phenyl group produced an analogue with a similar structure to i,3-dipropyl-8-(2-amino-4-chlorophenyl)xanthine (PACPX). A 2-phenyl substituent was favourable for interaction with the adenosine receptor. A number of pyrazolo(3,4-d)pyrirnidine analogues of 4,6-bis-a-carbamoylethylthio-i-phenylthiopyrazolo(3,4-d)pyrinhidine (DJB-KK) has also been synthesised and tested for Aj adenosine receptor affinity. 4,6-Bis-alkylthio-1-phenylpyrazolo(3,4-d)pyrimidines with a-carbamoylethyl and u-carbamoylpropyi groups were compared. The additional methyiene of the a-carbamoylpropyl group produced increased adenosine receptor affinity. 6-a-Carbamoylethylthio-4-mercapto-1-phenylpyrazolo(3,4-d)pyrimidine and 4-cc-carbamoylethylthio- i-phenylpyrazolo(3,4-dlpyrimidine were compared. Substitution of the C-6 position maintained activity, while substitution of the C-4 reduced activity.
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Jackson, Leila J. "The dynamic regulation of the low affinity IGE receptor by toll like receptor and B cell receptor agonists /." Connect to full text via ProQuest. Limited to UCD Anschutz Medical Campus, 2008.

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Thesis (Ph.D. in Immunology) -- University of Colorado Denver, 2008.
Typescript. Includes bibliographical references (leaves 122-129). Free to UCD Anschutz Medical Campus. Online version available via ProQuest Digital Dissertations;
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Sundaramoorthy, Meena. "MODULATION OF HIGH AFFINITY HORMONE BINDING TO LH/CG RECEPTOR." UKnowledge, 2002. http://uknowledge.uky.edu/gradschool_theses/209.

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Precise control of physiological phenomena is performed by various kinds of receptormediated signaling. The vast majority of receptors belong to the superfamily of G proteincoupled receptors (GPCRs), which form one of the largest protein families. In theclassical model of GPCR signaling, stimulation of seven transmembrane spanning GPCRleads to the activation of heterotrimeric G proteins, which dissociate into a and bgsubunits. The subunits activate effector molecules, which include second messengergenerating systems, giving rise to various kinds of cellular responses. The LH/CGreceptor is a member of the glycoprotein hormone receptor family along with the FSHand TSH receptors, which belongs to the GPCR superfamily. Human chorionicgonadotropin (hCG) binds to the exodomain of LH/CG receptor and the resulting hCGexodomaincomplex is thought to interact with the endodomain of the receptor to bringabout hormone signal.Unfortunately, little evidence is available for the precise hormonecontact points in the exo domain and endo domain of the receptor. The affinity ofhormone binding to the exodomain was enhanced when the endodomain was truncated.This suggests that the endodomain modulates the hormone binding to the exodomain ofthe receptor. To understand this, the role of exoloop 2 on the modulation of high affinityhormone binding to the exodomain was studied using photoaffinity labeling technique.
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Smith, Lucy. "Investigating inhibitors of the IgE:high affinity receptor protein-protein interaction." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/44210.

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The protein-protein interaction (PPI) between immunoglobulin E (IgE) and its high affinity receptor (FcεRI) is an important part of the allergic response. Inhibition of the IgE:FcεRI interaction is a key strategy for the development of allergy treatments. This PPI has been validated as a therapeutic target by the humanised monoclonal antibody omalizumab, which binds to IgE and prevents the formation of the IgE:FcεRI complex and has proved successful at treating allergic asthma. However, small molecule inhibitors of the IgE:FcεRI PPI that are orally available would be a more desirable form of treatment. This thesis describes the design, synthesis and testing of two series of inhibitors of the IgE:FcεRI interaction; small molecules based on the natural product aspercyclide A and short, linear peptides based on a key binding epitope of FcεRI. It also describes the development of a high-throughput time resolved fluorescence resonance energy transfer (TR-FRET) assay to test inhibitors and subsequent X-ray crystallography and SPR experiments to further investigate the mode of action of the inhibitors. An analogue of aspercyclide A has shown inhibition of the IgE:FcεRI interaction in the micromolar range and an improved potency compared to the natural product itself. A number of 8-residue, linear peptides have been found to inhibit the IgE:FcεRI PPI in the micromolar range when tested in the TR-FRET assay. The most potent peptide has been biotinylated and immobilised for SPR experiments with IgE and FcεRI. These SPR experiments suggest that the peptide inhibits the IgE:FcεRI interaction by binding to the high affinity receptor rather than to IgE.
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Turner, Helen Cathryn. "Signal transduction by the high affinity receptor for immunoglobulin E, FcER1." Thesis, University College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301134.

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Mueller, Thomas. "Systems for measuring B cell receptor affinity maturation in germinal centres." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7130/.

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Germinal Centres (GCs) play a central role in adaptive immunity; involving processes of cell migration, clonal expansion, hypermutation, and selection. To elucidate the role of affinity in regulating these processes, a technique for measuring B cell receptor affinity maturation in GCs in situ was developed. To facilitate interrogation of individual antibody-antigen interactions, atomic force microscopy (AFM) was chosen, offering nanometre positional resolution, and pico-Newton force sensitivity. Specificity of gold-coated AFM cantilevers towards the targeted receptors was achieved via a bespoke modification scheme, using self-assembled amine-terminated alkanethiol to facilitate attachment of the receptor specific antigen NP. Influences on molecule deposition and subsequent NP addition were investigated, as were control measures facilitating identification of successful modifications (Chapter 4). Effects of sample preparation techniques on AFM adhesion measurements were investigated (Chapter 5). Subsequently, the developed AFM technique was applied in interrogation of B cells and hybridomas – expressing receptors of varying affinity towards NP – and two GCs in tissue sections (Chapter 6). For the automated and unbiased evaluation of large amounts of varying AFM data, bespoke data analysis methods were developed. The project finds that AFM is capable of quantifying specific antibody-antigen interactions, but was unable to measure these in tissue sections. Possible reasons preventing such measurements are discussed.
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Timm, David Eugene. "Conformation, stability and interactions of the neurotrophins and the low-affinity neurotrophin receptor." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1057179020.

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Wahlström, Niklas. "Synthesis of indoles, bisindoles and indolocarbazoles : high affinity aryl hydrocarbon receptor ligands /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7140-016-8/.

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梁頌偉 and Chung-wai Leung. "Novel gene transfer vector targeted high affinity IL-2 receptor bearing cell." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31226280.

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Leung, Chung-wai. "Novel gene transfer vector targeted high affinity IL-2 receptor bearing cell /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25248698.

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Books on the topic "Receptor affinity"

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Ghaderi, Abbas Ali. Functional study of the low affinity IgE receptor (Fc[epsilon]RII/CD23) on human B lymphocytes. Birmingham: University of Birmingham, 1990.

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H, Gronemeyer, ed. Affinity labelling and cloning of steroid and thyroid hormone receptors. Weinheim, Federal Republic of Germany: VCH, 1988.

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Naples, Mark. Determinants of high affinity ligand binding to the group III metabotropic glutamate receptors. Ottawa: National Library of Canada, 2001.

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Clarke, Wendy Elizabeth. Intracellular compartmentalisation of fibroblast growth factor-2 and associated high and low affinity receptors after cerebral injury to the adult rat brain. Birmingham: University of Birmingham, 1999.

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Marelius, John. Computational Prediction of Receptor-Ligand Binding Affinity in Drug Discovery. Uppsala Universitet, 2000.

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Sardinia, Michael Francis. AT₄ receptor binding characteristics: A study of the structural requirements of the angiotensin IV peptide requisite for high affinity, specific ligand-receptor interaction. 1994.

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Verotoxin-globotriosylceramide binding: Receptor affinity purification and the effect of membrane environment on toxin binding. Ottawa: National Library of Canada, 1993.

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Khan, Samina E. An investigation of structure activity effects of D-ring substitution of estradiol on estrogen receptor affinity. 1992.

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Ren, Ke, and Ronald Dubner. The first crystal structure of an ionotropic glutamate receptor ligand-binding core. Edited by Paul Farquhar-Smith, Pierre Beaulieu, and Sian Jagger. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198834359.003.0032.

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The known functional ionotropic glutamate receptors (iGluRs) are composed of three major subtypes: AMPA, NMDA, and kainate. In 1998, in the landmark paper discussed in this chapter, Armstrong et al. provided the first crystal structure of an iGluR-subunit ligand-binding core, the S1S2 region of the rat GluA2 ‘flop’ isoform. They solved its structure with X-ray crystallography from selenomethonine crystals. They also identified residues involved in kainate binding, analysed allosteric sites that regulate affinity and specificity of the agonist, and mapped potential subunit–subunit interaction sites. They also proposed that binding of different agonists may result in variable degrees of domain closure. This work has profound impact on the field and it has been importantly cited. Subsequently, numerous high-resolution crystal structures of ligand-binding domains of iGluRs in complex with ligands, both agonists and antagonists, have been solved.
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Vitamin D3 Analogues with Low Vitamin D Receptor Binding Affinity Regulate Chondrocyte Proliferation, Proteoglycan Synthesis, and Protein Kinase C Activity. Storming Media, 1997.

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Book chapters on the topic "Receptor affinity"

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Manz, Bernhard, and Kunhard Pollow. "Dexamethasone-Biotin Affinity Probes." In Receptor Purification, 23–35. Totowa, NJ: Humana Press, 1990. http://dx.doi.org/10.1007/978-1-4612-0477-0_2.

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Nachman-Clewner, Michele, Cheryl Spence, and Pascal Bailon. "Receptor-Affinity Chromatography (RAC)." In Molecular Interactions in Bioseparations, 139–49. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4899-1872-7_9.

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Novick, Daniela, Dina G. Fischer, and Menachem Rubinstein. "Purification of the Human Interferon-γ Receptor by Ligand Affinity." In Receptor Purification, 459–81. Totowa, NJ: Humana Press, 1990. http://dx.doi.org/10.1007/978-1-4612-0461-9_24.

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Spence, Cheryl L., and Pascal Bailon. "Fluidized-Bed Receptor-Affinity Chromatography." In Methods in Molecular Biology, 25–39. Totowa, NJ: Humana Press, 2000. http://dx.doi.org/10.1007/978-1-60327-261-2_3.

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Locatelli-Hoops, Silvia C., and Alexei A. Yeliseev. "Use of Tandem Affinity Chromatography for Purification of Cannabinoid Receptor CB2." In Protein Affinity Tags, 107–20. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-1034-2_9.

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Panayotou, George, J. Justin Hsuan, and Michael D. Waterfield. "Ligand- and Antibody-Affinity Purification of the Epidermal Growth Factor Receptor." In Receptor Purification, 289–302. Totowa, NJ: Humana Press, 1990. http://dx.doi.org/10.1007/978-1-4612-0461-9_14.

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Besch, Henry R., Chun Hong Shao, and Keshore R. Bidasee. "Ryanoids, Receptor Affinity and RYR Channel Subconductance." In Ryanodine Receptors, 179–89. Boston, MA: Springer US, 2005. http://dx.doi.org/10.1007/0-387-23188-9_18.

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Frömmichen, Torsten, André Zimmermann, Thomas Nann, Albrecht Sippel, and Gerald A. Urban. "Development of Receptor Based Affinity Microassay." In Transducers ’01 Eurosensors XV, 366–69. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-59497-7_87.

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Viel, Gerhard T., Kees Ensing, and Rokus A. de Zeeuw. "Determination of Receptor–Ligand Affinity Constants." In Quantitative Analysis of Biospecific Interactions, 121–31. London: Routledge, 2021. http://dx.doi.org/10.4324/9781315824994-7.

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Puett, David, and Krassimira Angelova. "Determining the Affinity of Hormone−Receptor Interaction." In Methods in Molecular Biology, 1–20. Totowa, NJ: Humana Press, 2009. http://dx.doi.org/10.1007/978-1-60327-378-7_1.

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Conference papers on the topic "Receptor affinity"

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"Estrogen receptor binding affinity estimated by QSAR." In International Institute of Chemical, Biological & Environmental Engineering. International Institute of Chemical, Biological & Environmental Engineering, 2015. http://dx.doi.org/10.15242/iicbe.c0615100.

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Simone, E. R., T. A. Davies, N. A. Zabe, S. M. Greenberg-seperaky, and N. E. Larsen. "EARLY PLATELET-THROMBIN RECEPTORS AND THEIR FUNCTIONS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643730.

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Human platelets possess less than 1000 high affinity [Kd=10-9]and 50-100,000 receptors of lower [Kd=10-7] affinity for o(α-thrombin. The selective derivatization of thrombin with the bifunctional crosslinking agent, DNCO, has enabled us to identify these receptorsvia covalent binding of either active siteinhibited tosyllyslmethylketothrombin (TLCK-T) or active Ctf-thrombin (T).Kinetic studies of the inhibition of the platelet-thrombin response by covalently and noncovalently bound TLCK-T have helped to elucidate the roles of the high and low affinity thrombin receptors. The activation parameters examined were initial membrane depolarization, cytoplasmic alkalinization,dense granule secretion of serotonin and lysosomal secretion of β-glucuronidase.Isolation and characterization of the thrombin receptors after covalent photocoupling of the TLCK-T or active T- were performed after solubilization by gel filtration. The intact, high affinity receptor moiety, a glycoprotein, has an approximate molecular weight of∽lSO.OOO daltons; occasionally this protein is found as a dimer of ∽360,000 daltons. When exposed to o(α-T the receptor undergoes proteolysis, leaving a protein of∽80,000 daltons and releasing the remaining glycoprotein into the medium.Higher doses of active T have been shown to bind with lower affinity to a larger protein of approximate molecular weight 600,000 daltons anda smaller protein of 46,000 daltons. Both proteins are nonsusceptible to thrombin proteolysis. Reduction and alkylation of the600,000 dalton complex yielded two and possibly three high molecular weight components (200,000, 160,000, and possibly 145,000daltons) which may correspond to previously suggested GP-Ia and GP-Ib of the GP-I complex. Under different solubilization conditions, two other membrane proteins have been found to be part of the GP-I complex; one which is not a glycoprotein, GP-Ic, while the other is associated with the glycocalyx and is called glycocalicin. Glycocalicin and GP-Icdo inhibit thrombin binding,implying that the low affinity receptor is indeed the previously suggested GP-I complex and does not appear to be directly involved withplatelet activation.Examination of the effect of dose and duration of incubation with non-covalently binding TLCK-T on subsequent α-thrombin response suggests the existence of positive cooperativity among thrombin receptors.Although TLCK-T has the same affinity for platelets (Kd) as T , the rateof binding and therefore that of dissociation are lower. Thus for incubation times of 1 minute or less with up to a 2x saturating TLCK-T dose, the subsequent depolarization response to a saturating T dose was enhanced. Exposure to higher TLCK-T (5x saturating)doses led to significant inhibition.Verification of the potentiation observed in noncovalent TLCK-T studies was performed using TLCK-T covalently bound to the platelet receptor with DNCO. Several hundred thrombin molecules were bound to the platelet when a subsaturating dose of TLCK-T(0.0025 U/ml) was used to crosslink, whileseveral thousand resulted with a saturating (0.05 U/ml) TLCK-T dose. Positive cooperativity was observed with low αT doses (0.005 U/ml) when several hundred high affinity receptors are blocked. The parameters studied which exhibited this positive cooperativity were depolarization, pH change and serotonin secretion, α-Glucuronidase secretion was normal. The presence and degreeof enhancement were donor-variableand suggest different threshhold thrombin dose requirements. The enhancement observed can be attributed to either an increased rate of binding (increased affinity) or to an increased number of exposed binding sites. Since little difference was found between the number of TLCK-T molecules bound after30 versus 60 seconds, we conclude that thepotentiation is more likely due to an increased number of exposed binding sites. Results from covalent crosslinks using a fluorescein and rhodamine labeled-TLCK-T and the fluorescence activated cellsorter support this hypothesis. The sensitization of the high affinity binding sitesby partial occupancy implies these bindingsites are responsible for depolarization, pH change and dense granule secretion (the rapid initial activation response), while βglucuronidase secretion, a secondary response, is otherwise controlled.
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Bowry, S. K., and M. Tepel. "NON-REVERSIBLE BINDING OF 5'-p-FLUOROSULFONYLBENZOYL ADENOSINE TO WASHED INTACT PLATELETS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643506.

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ADP is an important in vivo mediator of platelet aggregation. The identification and estimation of a finite number of receptor sites has been made difficult by the reversible nature of the action of ADP on platelets and because ADP can be degraded by enzymes on the platelet surface. Analogues of ADP have therefore been commonly used to study the ADP receptor. We investigated the validity of using 5'-p-fluorosulfonylbenzoyl adenosine (FSBA), an affinity analogue of ADP that inhibits ADP-induced aggregation, for studying the ADP receptor on intact washed platelets. Binding of labelled FSBA, like for ADP, was saturable. Scatchard plot analyses of equilibrium binding data indicated, positive cooperativity; the apparent affinity (2.4 × 10−6) correlated well with the amount of ADP required to cause aggregation and with the value obtained from aggregation studies. However, the platelet bound FSBA was not displaceable with excess unlabelled FSBA indicating non-reversibility of ligand binding. As the minimal criteria for receptor identification (specificity, saturability and reversibility) are not fulfilled, the usage of FSBA to study the ADP receptor must be treated with caution. As FSBA is able to bind covalently to at least four polypeptides in isolated platelet membranes, a finite number of receptors cannot be postulated using FSBA. Furthermore, positive cooperativity, as indicated by the Scatchard plots, may be explained in terms of specific non-receptor binding. As the ADP receptor cannot be identified with any degree of certainty, the possibility therfore exists that the mechanism by which ADP initiates aggregation by rearrangement of platelet membrane proteins without binding to a single protein receptor.
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Bakhit, C., D. Lewis, R. Billings, and B. Malfroy. "CELLULAR CATABOLISM OF RECOMBINANT TISSUE-TYPE PLASMINOGEN ACTIVATOR: IDENTIFICATION AND CHARACTERIZATION OF A NOVEL HIGH AFFINITY UPTAKE SYSTEM ON RAT HEPATOCYTES." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644400.

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The uptake, internalization and intracellular degradation of 125I-labeled rt-PA (125I-rt-PA) by isolated rat hepatocytes was investigated. Incubation at 37°C resulted in internalization of 125I-rt-PA, followed by the appearance of labeled trichloroacetic acid-soluble (TCA) material in the inclubation media due to degradation of rt-PA. Degradation of rt-PA was inhibited by the presence of NH4Cl (10mM) or chloroquine (ImM) (lysosoma tropic agents) in the incubation media. This suggests that rt-PA degradation occurs intracellularly, perhaps within the lysosomes. 125I-rt-PA was taken up by rat hepatocytes through a specific, high affinity mechanism. Scatchard analysis of the data indicated that 106 molecules of rt-PA were taken up per cell/hour and the calculated dissociation constant was lOnM. Uptake of 125I-rt-PA was not inhibited by glycopeptides isolated from rt-PA nor by several other glycoproteins known to be cleared by identified hepatic receptors. These results suggest that the uptake of rt-PA by rat hepatocytes involves a receptor specific for t-PA and is not mediated by a carbohydrate specific receptor.
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Lee, Jong-Min, Na-Na Jeong, Vasanthan Devaraj, Minjun Kim, Samir Adhiari, Won-Geun Kim, Jong-Ryeul Sohn, Donghan Lee, and Jin-Woo Oh. "Selective surface-enhanced Raman scattering platform with functional phage as a bio-receptor." In JSAP-OSA Joint Symposia. Washington, D.C.: Optica Publishing Group, 2019. http://dx.doi.org/10.1364/jsap.2019.18p_e208_12.

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Phage display, an attracting attention, and recipient of 2018 Nobel Prize in Chemistry is a method for screening functional bacteriophages (phage) with high binding affinity for the target molecules, can enhance selectivity and sensitivity when applied to sensors [1]. In particular, the functional phage is expected to be suitable for the SERS plat-form because low selectivity is a problem even though the SERS platform is known to have high sensitivity. Here we present a method for applying functional phage to the SERS platform as a bio-receptor [2]. The binding affinity of the functional phage for the target substance was verified by the isotherm titration calorimetry (ITC). As a result, it was confirmed that the selectivity and sensitivity of the SERS platform into which the phage was introduced were enhanced in proportion to the binding affinity.
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Broeseker, T. A., M. D. P. Boyle, and R. Lottenberg. "PATHOGENIC BACTERIA HAVE HIGH AFFINITY RECEPTORS SPECIFIC FOR PLASMIN." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644391.

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Binding of the key fibrinolytic enzyme, plasmin, to certain pathogenic group A streptococci was studied. In these experiments the ability of a group A streptococcal strain, 64/14, to bind either 125I-human plasminogen or the same label following activation with urokinase was measured. It was found that this strain bound <10% of the labeled plasminogen but >70% of labeled plasmin. This property distinguishes the plasmin receptor from streptokinase. These bacteria did not express a common serine protease receptor/inhibitor since they failed to bind labeled trypsin or urokinase. Maximal binding of plasmin occurred between pH 6.0 and 8.0 and in the ionic strength range of 50-200 mM salt. The Kd of plasmin binding to bacteria was approximately 10-10 M at pH 7.4 in 150 mM salt. This was determined by a non-linear least squares analysis of equilibrium binding data. Binding was reversibly inhibited by either epsilon aminocaproic acid (I50 of 0.2 mM) or lysine (I50 of 3.0 mM) suggesting the involvement of the high affinity lysine binding site of plasmin in its binding to bacteria. Bacterial bound plasmin retains its enzymatic activity, being capable of cleaving chromogenic substrates and solubilizing a fibrin- clot. The bacterial bound enzyme activity was inhibited by the low molecular weight inhibitors aprotinin and phe-pro-arg chloromethyl ketone but not by alpha-2 plasmin inhibitor. The ability of bacteria to acquire membrane associated proteolytic activity which cannot be physiologically inhibited may contribute to their tissue invasive properties.
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Wachtfogel, Yanina T., Yizhar Floman, Meir Liebergall, Robert W. Colman, and Amiram Eldor. "PLATELET ALPHA2-ADRENERGIC RECEPTOR ABNORMALITIES IN PATIENTS WITH IDIOPATHK: SCOLIOSIS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644567.

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Idiopathic scoliosis is a genetic multisystem disease involving skeletal, biochemical, central nervous svstem, muscle and blood platelet abnormalities. Platelets of patients with idiopathic scoliosis have been shown to have decreased adenosine diphosphate and epinephrine-induced aggregation. Similarities between the contractile protein system of platelets and muscle have made the platelet a popular model for certain aspects of muscle physiology. This study confirmed that 64% of the patient platelets tested exhibited a significantly decreased sensitivity to aggregation bv epinephrine. In seven of the eleven patients studied, epinephrine induced aggregation was markedly decreased, i.e., the threshold of agonist was markedly elevated ≥11 uM). The geometric mean concentration of epinephrine required to produce complete second-wave aggregation in idiopathic scoliosis patients was 8μM. as compared to a control concentration of luM. We therefore examined the platelet alpha2-adrenergic receptors of 17 patients with idiopathic scoliosis bv measuring ligand binding using the selective antagonist, methyl yohimbine. Platelets from healthv individuals had 185 ± 16 sites per platelet with a Kd of 1.90 ± 0.32 nM, while patients with idiopathic scoliosis had 54 ± 22 sites per platelet with a of 1.02 ± 0.03 nM. The number of binding sites per platelet in idiopathic scoliosis patients were significantly decreased (p < 0.05) as compared to controls , while the was not significantly different (p > 0.05) between the two groups. Seven of these patients exhibited a significant decrease (p < 0.05) in the number of alpha2-adrenergic receptors on their platelets while the binding in 7 additional patients was undetectable.Three patients exhibited normal receptor number and affinity as compared to normal individuals. This study indicates a profound alteration in the number and function of the alpha2-adrenergic receptors in platelets of patients with idiopathic scoliosis and indicates the functional heterogeneity of the receptor disorder. Further investigation of platelet abnormalities may give insight into the putative muscle defects.
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Bowry, S. X. "ENHANCED ASSOCIATION OF FIBRINOGEN WITH ITS PLATELET RECEPTOR DUE TO SODIUM CITRATE INDICATION FOR ONE FIBRINOGEN RECEPTOR ONLY." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643701.

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Washed platelet suspensions are almost always prepared from blood anticoagulated with sodium citrate. As citrate has been implicated to affect platelet function and as estimates of the number of fibrinogen (Fbg) bindingsites on platelets range from 4,700 -82,500, we examined the involvement of citrate on the platelet-fibrinogen interaction. The binding of 125-1-fibrinogen to washed platelets from citrated blood (PCB) and thosefrom gel-filtered non-anticoagulated blood (PNB) from the same donor showed linear Scatchard plots for PNB and curvilinear plots for PCB. Assuming the presence of two classes of bindingsites, a high_.affinity site (5,540±760 molecules/ platelets; Kd, 1.29 x 10-7 M) and low affinity site (32,070 α 6,520 molecules/platelet; Kd 1.02 x 10-6 M) were determined for PCB. However, PNB indicated a single class of binding sites with 16,480α 2,800 Fbg molecules/platelet.When blood from one donor was collected into 10 mM and 20 mM citrate, increased binding of Fbg was observed onplatelets exposed to 20 mM citrate. The effects of citrate appear to be on theplatelet Fbg receptor since non-specific binding was not affected by the citrate. As no 14-C-citric acid binding to platelets was observed, citrate may affect the receptors without binding to the platelets. The dependence of binding on the pHof thecitrate suggests ionic interactions between platelets and citrate. Different amounts of Fbg were bound when four different preparations of sodium citrate varying in concentration and pH were used. Ourdata suggest that acombination of thedirect effects of citrate on the Fbg bindingof platelets, together with the variable concentrations and pH of the different citrate preparations routinelyused toanticoagulate blood, may explain why some investigators obtain upwardly concave Scatchard plotswhile others obtain linear plots. Ourresultsindicate that the major reasonfor the disparities in the Fbg binding datais due to the effects of citrate on platelets.
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Modesti, P. A., A. Fortini, M. Boddi, L. Poggesi, R. Abbate, and G. F. Gensini. "REVERSIBLE REDUCTION OF PLATELET PROSTACYCLIN BINDING SITES AFTER ILOPROST INFUSION IN MAN." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643454.

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The reduction of platelet sensitivity to prostacyclin (PGI2), observed in man after the infusion of PGI2 analogues, could suggest the presence of a down regulation mechanism for PGI2 platelet receptors. Robertson (1980) have shown a dcwn-regulaticn of PGE2 binding after PGE2 infusion in rat and Leigfrt (1985) have provided evidence of an homologous desensitizaticn to PGI2 in cultured cells, but direct evidences of PGI2 receptors dcwn-regulaticn in man are lacking.This work was performed to study the behaviour of PGI2 platelet receptors after a PGE2 analogue infusion in man.Eight subjects with peripheral artery disease (stage IV according to Fontaine) treated for 14 consecutive days with six hours iv infusion of Iloprost (Sobering, FRG) at 2 ng/Kg/min were studied. Platelet studies were performed an the 1st, 2nd, 7th and 14th day of therapy, blood sanples being collected immediately before the beginning (between 8.00 and 9.00 a.m.), at the end and 6 and 18 hours (the following morning) after the end of the infusion. PGI2 platelet receptors were investigated by a direct radioligand binding assay. PGI2 inhibitory dose 50 (I.D.50) was evaluated in platelet aggregation induced by ADP 5 ¼M.After six hours of Iloprost infusion a significant reduction of high affinity PGI2 platelet receptor (HAR) nunber was observed (p<0.005) without any change of affinity for the ligand. After 6 hours from the end of the infusion the reduction of the HAR was still statistically significant (p<0.05). The following morning the receptor nunber was restored (n.s.). After one and two weeks from the beginning of the treatment the basal values of PGI2 HAR were not significantly changed from the values recorded on the first day of therapy.PGI2 I.D.50 after the infusion was significantly increased when compared to the basal values (p<0.01). Six hours later the basal sensitivity was restored (n.s.). Eighteen hours later, the following morning PGI2 I.D.50 were still not significantly changed in comparison to the basal values.These data are suggestive for the presence of a reversible down regulation mechanism for the PGI2 receptors.
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Colella, L., J. Deuquet, C. Beyer, J. Frohlich, G. van der Goot, and P. Renaud. "Label-free IDE-based impedance spectroscopy for the investigation of receptor-protein affinity." In 2013 Transducers & Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS & EUROSENSORS XXVII). IEEE, 2013. http://dx.doi.org/10.1109/transducers.2013.6627227.

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Reports on the topic "Receptor affinity"

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Liu, Jingwen. Role of High-Affinity Oncostatin M Receptor in Prevention of Breast Cancer Cell Growth. Fort Belvoir, VA: Defense Technical Information Center, April 1995. http://dx.doi.org/10.21236/ada295676.

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Boisclair, Yves R., and Arieh Gertler. Development and Use of Leptin Receptor Antagonists to Increase Appetite and Adaptive Metabolism in Ruminants. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7697120.bard.

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Objectives The original project had 2 major objectives: (1) To determine the effects of centrally administered leptin antagonist on appetite and adaptive metabolism in the sheep; (2) To develop and prepare second-generation leptin antagonists combining high binding affinity and prolonged in vivo half-life. Background Periods of suboptimal nutrition or exaggerated metabolic activity demands lead to a state of chronic energy insufficiency. Ruminants remain productive for a surprisingly long period of time under these circumstances by evoking adaptations sparing available energy and nutrients. The mechanism driving these adaptations in ruminant remains unknown, but could involve a reduction in plasma leptin, a hormone acting predominantly in the brain. In laboratory animals, reduced leptin signaling promotes survival during nutritional insufficiency by triggering energy sparing adaptations such as reduced thyroid hormone production and insulin resistance. Our overall hypothesis is that similar adaptations are triggered by reduced leptin signaling in the brain of ruminants. Testing of this hypothesis in ruminants has not been possible due to inability to block the actions of endogenous leptin and access to ruminant models where leptin antagonistic therapy is feasible and effective. Major achievements and conclusions The Israeli team had previously mutated 3 residues in ovine leptin, with no effect on receptor binding. This mutant was renamed ovine leptin antagonist (OLA) because it cannot activate signaling and therefore antagonizes the ability of wild type leptin to activate its receptor. To transform OLA into an effective in vivo antagonist, the Israeli made 2 important technical advances. First, it incorporated an additional mutation into OLA, increasing its binding affinity and thus transforming it into a super ovine leptin antagonist (SOLA). Second, the Israeli team developed a method whereby polyethylene glycol is covalently attached to SOLA (PEG-SOLA) with the goal of extending its half-life in vivo. The US team used OLA and PEG-SOLA in 2 separate animal models. First, OLA was chronically administered directly into the brain of mature sheep via a cannula implanted into the 3rdcerebroventricule. Unexpectedly, OLA had no effect of voluntary feed intake or various indicators of peripheral insulin action but reduced the plasma concentration of thyroid hormones. Second, the US team tested the effect of peripheral PEG-SOLA administration in an energy sensitive, rapidly growing lamb model. PEG-SOLA was administered for 14 consecutive days after birth or for 5 consecutive days before sacrifice on day 40 of life. Plasma PEG-SOLA had a half-life of over 16 h and circulated in 225- to 288-fold excess over endogenous leptin. PEG-SOLA administration reduced plasma thyroid hormones and resulted in a higher fat content in the carcass at slaughter, but had no effects on feed intake, body weight, plasma glucose or insulin. These results show that the team succeeded in developing a leptin antagonist with a long in vivo half-life. Moreover, in vivo results show that reduced leptin signaling promotes energy sparing in ruminants by repressing thyroid hormone production. Scientific and agricultural implications The physiological role of leptin in ruminants has been difficult to resolve because peripheral administration of wild type leptin causes little effects. Our work with leptin antagonists show for the first time in ruminants that reduced leptin signaling induces energy sparing mechanisms involving thyroid hormone production with little effect on peripheral insulin action. Additional work is needed to develop even more potent leptin antagonists, to establish optimal administration protocols and to narrow down phases of the ruminant life cycle when their use will improve productivity.
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Chen, Yona, Jeffrey Buyer, and Yitzhak Hadar. Microbial Activity in the Rhizosphere in Relation to the Iron Nutrition of Plants. United States Department of Agriculture, October 1993. http://dx.doi.org/10.32747/1993.7613020.bard.

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Iron is the fourth most abundant element in the soil, but since it forms insoluble hydroxides at neutral and basic pH, it often falls short of meeting the basic requirements of plants and microorganisms. Most aerobic and facultative aerobic microorganisms possess a high-affinity Fe transport system in which siderophores are excreted and the consequent Fe complex is taken up via a cognate specific receptor and a transport pathway. The role of the siderophore in Fe uptake by plants and microorganisms was the focus of this study. In this research Rhizopus arrhizus was found to produce a novel siderophore named Rhizoferrin when grown under Fe deficiency. This compound was purified and its chemical structure was elucidated. Fe-Rhizoferrin was found to alleviate Fe deficiency when applied to several plants grown in nutrient solutions. It was concluded that Fe-Rhizoferrin is the most efficient Fe source for plants when compared with other among microbial siderophores known to date and its activity equals that of the most efficient synthetic commercial iron fertilizer-Fe EDDHA. Siderophores produced by several rhizosphere organisms including Rhizopus Pseudomonas were purified. Monoclonal antibodies were produced and used to develop a method for detection of the siderophores produced by plant-growth-promoting microorganisms in barley rhizosphere. The presence of an Fe-ferrichrome uptake in fluorescent Pseudomonas spp. was demonstrated, and its structural requirements were mapped in P. putida with the help of biomimetic ferrichrome analogs. Using competition experiments, it was shown that FOB, Cop B and FC share at least one common determinant in their uptake pathway. Since FC analogs did not affect FOB or Cop-mediated 55Fe uptake, it could be concluded that these siderophores make use of a different receptor(s) than FC. Therefore, recognition of Cop, FOB and FC proceeds through different receptors having different structural requirements. On the other hand, the phytosiderophores mugineic acid (MA and DMA), were utilized indirectly via ligand exchange by P. putida. Receptors from different biological systems seem to differ in their structural requirements for siderophore recognition and uptake. The design of genus- or species-specific drugs, probes or chemicals, along with an understanding of plant-microbe and microbe-microbe relationships as well as developing methods to detect siderophores using monoclonal antibodies are useful for manipulating the composition of the rhizosphere microbial population for better plant growth, Fe-nutrition and protection from diseases.
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Wisniewski, Michael, Samir Droby, John Norelli, Dov Prusky, and Vera Hershkovitz. Genetic and transcriptomic analysis of postharvest decay resistance in Malus sieversii and the identification of pathogenicity effectors in Penicillium expansum. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597928.bard.

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Use of Lqh2 mutants (produced at TAU) and rNav1.2a mutants (produced at the US side) for identifying receptor site-3: Based on the fact that binding of scorpion alpha-toxins is voltage-dependent, which suggests toxin binding at the mobile voltage-sensing region, we analyzed which of the toxin bioactive domains (Core-domain or NC-domain) interacts with the DIV Gating-module of rNav1.2a. This analysis was based on the assumption that the dissociation of toxin mutants upon depolarization would vary from that of the unmodified toxin should the substitutions affect a site of interaction with the channel Gating-module. Using a series of toxin mutants (mutations at both domains) and two channel mutants that were shown to reduce the sensitivity to scorpion alpha-toxins, and by comparison of depolarization-driven dissociation of Lqh2 derivatives off their binding site at rNav1.2a mutant channels we found that the toxin Core-domain interacts with the Gating-module of DIV. Details of the experiments and results appear in Guret al (2011). Mapping receptor site 3 at Nav1.2a by extensive channel mutagenesis (Seattle): Since previous studies with photoaffinity labeling and antibody mapping implicated domains I and IV in scorpion alpha-toxin binding, Nav1.2 channel mutants containing substitutions at these extracellular regions were expressed and tested for receptor function by whole-cell voltage clamp. Of a large number of channel mutants, T1560A, F1610A, and E1613A in domain IV had ~5.9-, ~10.7-, and ~3.9-fold lower affinities for the scorpion toxin Lqh2, respectively, and mutant E1613R had 73-fold lower affinity. Toxin dissociation was accelerated by depolarization for both wild-type and mutants, and the rates of dissociation were also increased by mutations T1560A, F1610A and E1613A. In contrast, association rates for these three mutant channels at negative membrane potentials were not significantly changed and were not voltage-dependent. These results indicated that Thr1560 in the S1-S2 loop, Phe1610 in the S3 segment, and Glu1613 in the S3-S4 loop in domain IV participate in toxin binding. T393A in the SS2-S6 loop in domain I also showed a ~3.4-fold lower affinity for Lqh2, indicating that this extracellular loop may form a secondary component of the toxin binding site. Analysis with the Rosetta-Membrane algorithm revealed a three-dimensional model of Lqh2 binding to the voltage sensor in a resting state. In this model, amino acid residues in an extracellular cleft formed by the S1-S2 and S3-S4 loops in domain IV that are important for toxin binding interact with amino acid residues on two faces of the wedge-shaped Lqh2 molecule that are important for toxin action. The conserved gating charges in the S4 transmembrane segment are in an inward position and likely form ion pairs with negatively charged amino acid residues in the S2 and S3 segments (Wang et al 2011; Gurevitz 2012; Gurevitzet al 2013).
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