Showing papers on "Receptor published in 1984"
TL;DR: In rats ischemia of the forebrain induced by a 30-minute occlusion of the carotid artery, followed by 120 minutes of arterial reperfusion, produced ischemic lesions of selectively vulnerable pyramidal cells in both hippocampi.
Abstract: In rats ischemia of the forebrain induced by a 30-minute occlusion of the carotid artery, followed by 120 minutes of arterial reperfusion, produced ischemic lesions of selectively vulnerable pyramidal cells in both hippocampi. Focal microinfusion into the dorsal hippocampus of 2-amino-7-phosphonoheptanoic acid, an antagonist of excitation at the N-methyl-D-aspartate-preferring receptor, before ischemia was induced protected against the development of ischemic damage. It is proposed that excitatory neurotransmission plays an important role in selective neuronal loss due to cerebral ischemia.
1,721 citations
TL;DR: It is clear that detailed understanding of the mechanism of regulation of CAMP synthesis will soon be achieved from study of the interactions of purified components that have been reconstituted in lipid bilayers of defined composition.
1,645 citations
1,595 citations
TL;DR: The development of an immunocytochemical procedure suitable for localizing oestrophilin directly in frozen tissue sections or cells from human and several non-human sources is reported.
Abstract: Although it is widely accepted that specific intracellular receptor proteins are involved in the oestrogenic regulation of gene expression and growth in reproductive tissues, the precise nature of the regulation is poorly understood. Among the unresolved issues are the distribution and dynamics of the oestrogen receptor protein (oestrophilin) in target tissues in the presence and absence of oestrogens and antioestrogens. The use of radio-labelled and unlabelled receptor ligands to detect and measure oestrogen receptors in tissues has been complicated by the presence of other intracellular steroid-binding proteins1 and by the low concentration of receptors in responsive tissues. We report here the development of an immunocytochemical procedure that is suitable for localizing oestrophilin directly in frozen tissue sections or cells from human and several non-human sources. When monoclonal antibodies to oestrophilin were used to detect receptor in various oestrogen-sensitive tissues, specific staining was confined to the nucleus of all stained cells, suggesting that both cytosol and nuclear forms of the receptor protein may reside in the nuclear compartment.
1,404 citations
TL;DR: Given that T11 is the earliest T-lineage surface glycoprotein to appear in thymic ontogeny and is thus expressed before T3-Ti, the former may be involved in clonal expansion and/or differentiation during early development.
1,085 citations
TL;DR: It is shown that monoclonal antibodies against rat and human transferrin receptors label blood capillaries in the brain but not in other tissues, suggesting that transferrin receptor expression on neuronal and glial cells may allow transport of transferrin into brain tissues.
Abstract: The blood/brain barrier prevents the passive diffusion of proteins and metabolites from cerebral blood vessels into tissue spaces around neuronal and glial cells. To provide nutrients for these cells, transport mechanisms must exist and indeed have been demonstrated for metabolites. We now show that monoclonal antibodies against rat and human transferrin receptors label blood capillaries in the brain but not in other tissues. In the rat this labelling occurs after injection of antibody into the blood, thus the receptors seem to be accessible at the endothelial surface. It is possible that transferrin receptors are expressed on these cells to allow transport of transferrin (and thus iron) into brain tissues.
958 citations
TL;DR: It is suggested that the independently developed schemata for classification of dopamine receptors in either the central nervous and endocrine systems or the cardiovascular system are similar although maybe not completely identical.
942 citations
TL;DR: It is concluded that CR2 is the EBV receptor of human B lymphocytes, which recognize a Mr 145,000 B-lymphocyte membrane protein that is CR2.
Abstract: Identity of the Epstein-Barr virus (EBV) receptor with the complement receptor type 2 (CR2) was established in three sets of experiments using the monoclonal antibodies, HB-5 and anti-B2, which recognize a Mr 145,000 B-lymphocyte membrane protein that is CR2. First, the rank order for binding of fluoresceinated EBV to four lymphoblastoid cell lines (SB, JY, Raji, and Molt-4) was identical to the rank order for binding of HB-5 and anti-B2 by analytical flow cytometry. Second, pretreatment of cells with HB-5 followed by treatment with goat F(ab')2 fragments to mouse IgG blocked binding of fluoresceinated EBV on SB, a B-lymphoblastoid cell line. Virus attachment was not inhibited by HB-5 alone, second antibody alone, rabbit anti-C3b receptor, or UPC10 (an irrelevant monoclonal antibody). Third, transfer of CR2 from SB to protein A-bearing Staphylococcus aureus particles, to which HB-5 had been absorbed, conferred on them the specific ability to bind 125I-labeled EBV. We conclude that CR2 is the EBV receptor of human B lymphocytes.
914 citations
TL;DR: Since the proliferative characteristics of T cells are identical to those of both prokaryotic and all other eukaryotic cells, these findings provide a new model that accounts fully for the variables that determine cell cycle progression.
Abstract: Synchronized interleukin-2 receptor-positive T cells, homogeneous immunoaffinity-purified interleukin-2, and a monoclonal antibody to interleukin-2 receptors were used to show that only three factors are critical for T-cell cycle progression: interleukin-2 concentration, interleukin-2 receptor density, and the duration of the interleukin-2 receptor interaction. Since the proliferative characteristics of T cells are identical to those of both prokaryotic and all other eukaryotic cells, these findings provide a new model that accounts fully for the variables that determine cell cycle progression.
911 citations
TL;DR: It is found that cytoplasts prepared from GH3 cells contain little oestrogen-binding activity and that most of the unfilled oestrogens receptors are associated with the nuclear fraction, suggesting that the standard model is in error and that the unoccupied receptor is nuclear in the intact cell.
Abstract: According to the current model of steroid hormone action oestrogen is thought to bind to its receptor in the cytoplasm of target cells1,2 and the oestrogen–receptor complex is then translocated into the nucleus2–4. This model is based on evidence obtained in homogenized cell preparations in which free receptor is associated with the cytosol, whereas steroid-bound receptor is associated with the nuclear fraction. Some data suggest, however, that the unfilled receptor may reside in the nucleus, and that cytosolic localization represents an extraction artefact. We have now reinvestigated the subcellular distribution of unfilled oestrogen receptor using cytochalasin B-induced enucleation to obtain cytoplast and nucleoplast fractions from receptor-containing GH3 cells derived from rat pituitary tumours. We found that cytoplasts prepared from GH3 cells contain little oestrogen-binding activity and that most of the unfilled oestrogen receptors are associated with the nuclear fraction. We therefore suggest that the standard model is in error and that the unoccupied receptor is nuclear in the intact cell.
888 citations
TL;DR: An evaluation of investigations designed to elucidate regulatory mechanisms at acidic amino acid binding sites is made; hypotheses such as the Ca2+-activated protease hypothesis of long-term potentiation are assessed in terms of the new binding site/receptor classification scheme.
TL;DR: The human T-cell growth factor (interleukin-2) receptor is purified and cloned, sequenced and expressed cDNAs corresponding to this receptor and one gene, but two interleukIn-2 receptor mRNAs which differ in their polyadenylation signals are identified.
Abstract: We have purified the human T-cell growth factor (interleukin-2) receptor and have cloned, sequenced and expressed cDNAs corresponding to this receptor. We identify one gene, but two interleukin-2 receptor mRNAs which differ in their polyadenylation signals. We have isolated an additional cDNA that may correspond to an alternatively spliced mRNA that lacks a 216 base segment and appears to encode an altered membrane protein which cannot bind interleukin-2.
TL;DR: Two model systems for producing reversible glucocorticoid receptor depletion in the hippocampus are used and it is found that depletion of receptors without inducing cell loss results in corticosterone hypersecretion.
Abstract: The hippocampus is the principal target site in the brain for adrenocortical steroids, as it has the highest concentration of receptor sites for glucocorticoids. The aged rat has a specific deficit in hippocampal glucocorticoid receptors, owing in large part to a loss of corticoid-sensitive neurons. This deficit may be the cause for the failure of aged rats to terminate corticosterone secretion at the end of stress, because extensive lesion and electrical stimulation studies have shown that the hippocampus exerts an inhibitory influence over adrenocortical activity and participates in glucocorticoid feedback. We have studied whether it is the loss of hippocampal neurons or of hippocampal glucocorticoid receptors in the aged rat that contributes most to this syndrome of corticosterone hypersecretion. To do this, we used two model systems for producing reversible glucocorticoid receptor depletion in the hippocampus, and we found that depletion of receptors without inducing cell loss results in corticosterone hypersecretion. Furthermore, correction of the receptor deficit results in normalization of corticosterone secretion. These results focus attention on the hippocampus as an important glucocorticoid sensor in relation to the stress response. They also provide important new physiological correlates for the remarkable plasticity of the hippocampal glucocorticoid receptor system, which is under independent control by corticosterone and by vasopressin.
TL;DR: Extension of the IL-2 binding analysis to concentrations several thousand-fold higher than that necessary for the T cell proliferative response demonstrated the existence of a class (or classes) of low-affinity IL- 2 binding sites, which were found on activated T cells, several human and murine T cell lines and two examples of Tac-positive B cells.
Abstract: Interleukin 2 promotes proliferation of T cells by virtue of its interaction with a high-affinity cell surface receptor. This receptor is a 55,000 mol wt glycoprotein that is also recognized by the murine monoclonal antibody, anti-Tac. Quantitative binding studies with radiolabeled IL-2 and anti-Tac, however, initially indicated far more antibody binding sites per cell than IL-2 binding sites. Extension of the IL-2 binding analysis to concentrations several thousand-fold higher than that necessary for the T cell proliferative response demonstrated the existence of a class (or classes) of low-affinity IL-2 binding sites. Inclusion of the low-affinity IL-2 binding greatly reduced the quantitative discrepancy in the ligand binding assays. That the low-affinity binding, as well as the high-affinity interaction, was associated with the Tac molecule was indicated by the finding that the antibody could substantially or totally block the entire spectrum of IL-2 binding and by the finding that IL-2 could in turn block all radiolabeled anti-Tac binding. The low-affinity sites were found on activated T cells, several human and murine T cell lines and two examples of Tac-positive B cells. The physiological role of the low-affinity IL-2 binding sites and the molecular changes in the Tac protein that give rise to the affinity differences remain open to investigation.
TL;DR: Evidence is presented that glucocorticoid down-regulation may constitute a physiological phenomenon and was limited, in that exogenous corticosterone plus stress reduced receptor number no more than did stress alone.
Abstract: We have examined whether corticosterone receptor number within the brain can be regulated by its own ligand and whether such autoregulation reduces receptor number after the sustained secretion of corticosterone during repeated stress. Glucocorticoid receptors were measured in cytosolic preparations from acutely adrenalectomized rats using [1,2,6,7-3H] dexamethasone; maximal binding and receptor affinity parameters were determined by Scatchard analysis. Sustained elevations of circulating corticosterone, whether by repeated stress or exogenous corticosterone administration, did not change receptor affinity for [3H] dexamethasone, but significantly reduced cytosolic corticosterone receptor number. This reduction in total receptor number could not be attributed to residual tissue contamination with endogenous corticosterone after adrenalectomy or to translocation of cystosolic receptors to cell nuclei. The receptor reductions were anatomically specific, occurring in the hippocampus and amygdala, but not in ...
TL;DR: In the present study, the in vitro binding of 3H-SCH 23390 to specific striatal receptor sites has been characterized and saturable and stereospecific, and the results of both saturation and competition studies are consistent with the binding of this radioligand to a single striatal site.
TL;DR: The human interleukin-2 (IL-2) receptor was purified by affinity chromatography using the anti-Tac monoclonal antibody, and its N-terminal amino acid sequence was determined.
Abstract: The human interleukin-2 (IL-2) receptor was purified by affinity chromatography using the anti-Tac monoclonal antibody, and its N-terminal amino acid sequence was determined. Complementary DNA clones were isolated and sequenced to reveal the primary structure of the IL-2 receptor precursor, which has 272 amino acid residues. The receptor is separated into two domains by a putative 19-residue transmembrane region. Two mRNAs (1.4 and 3.5 kilobases) hybridizing to the cDNA clone were found in human T cells bearing the IL-2 receptor. The cDNA directed synthesis of the IL-2 receptor in COS cells.
TL;DR: It is shown that, over a 100,000-fold range of potencies, the activity of a pure soluble protein can be inhibited by 50% at anaesthetic concentrations which are essentially identical to those which anaesthetize animals.
Abstract: Most proteins are insensitive to the presence of anaesthetics at concentrations which induce general anaesthesia, while some are inhibited by certain agents but not others1. Here we show that, over a 100,000-fold range of potencies, the activity of a pure soluble protein (firefly luciferase) can be inhibited by 50% at anaesthetic concentrations which are essentially identical to those which anaesthetize animals. This identity holds for inhalational agents (such as halothane, methoxyflurane and chloroform), aliphatic and aromatic alcohols, ketones, ethers and alkanes. This finding is all the more striking in view of the fact that the inhibition is shown to be competitive in nature, with anaesthetic molecules competing with substrate (luciferin) molecules for binding to the protein. We show that the anaesthetic-binding site can accommodate only one large, but more than one small, anaesthetic molecule. The obvious mechanism suggested by our results is that general anaesthetics, despite their chemical and structural diversity, act by competing with endogenous ligands for binding to specific receptors.
Journal Article•
TL;DR: In this article, three anti-EGF receptor MoAbs were used in the present studies, and all three MoAbs inhibited A431 tumor growth in athymic mice, indicating that the antibody isotype and the site of binding on the EGF receptor are not determinants of antiproliferative activity in vivo.
Abstract: Monoclonal antibodies (MoAbs) were raised against epidermal growth factor (EGF) receptors on a human epidermoid carcinoma cell line, A431. Administration of anti-EGF receptor MoAbs inhibited tumor formation in athymic mice by A431 cells and by another epidermal carcinoma cell line, T222. When one of the same MoAbs was used in therapy against Li-7 (a human hepatoma) and HeLa cells (a cervical carcinoma), tumor growth was not affected. The number of EGF receptors on A431 cells was about 100-fold higher than on T222, Li-7, and HeLa cells, suggesting that the number of EGF receptors may not be an important determinant in suppressing tumor growth. Three anti-EGF receptor MoAbs were used in the present studies. MoAbs 528 (immunoglobulin G2a) and 225 (immunoglobulin G1) are capable of competing with EGF for receptor binding and inhibit proliferation of A431 cells in culture. The other MoAb, 455 (immunoglobulin G1), is incapable of blocking the binding of EGF to its receptors and has no effect on the proliferation of cultured A431 cells. All three MoAbs inhibited A431 tumor growth in athymic mice, indicating that the antibody isotype and the site of binding on the EGF receptor are not the determinants of antiproliferative activity in vivo. The observation that MoAb against the receptor for EGF is cytostatic rather than cytocidal in vitro against A431 cells, yet completely prevents tumor growth in vivo, suggests that some host animal responses also may be involved in the antitumor effect. MoAbs against growth factor receptors could provide useful immunotherapeutic agents.
TL;DR: The hormonal form of vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], at picomolar concentrations, inhibited the growth-promoting lymphokine interleukin-2, which is produced by human T lymphocytes activated in vitro by the mitogen phytohemagglutinin.
Abstract: The hormonal form of vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], at picomolar concentrations, inhibited the growth-promoting lymphokine interleukin-2, which is produced by human T lymphocytes activated in vitro by the mitogen phytohemagglutinin Other metabolites of vitamin D3 were less effective than 1,25(OH)2D3 in suppressing interleukin-2; their order of potency corresponded to their respective affinity for the 1,25(OH)2D3 receptor, suggesting that the effect on interleukin-2 was mediated by this specific receptor The proliferation of mitogen-activated lymphocytes was also inhibited by 1,25(OH)2D3 This effect of the hormone became more pronounced at later stages of the culture These findings demonstrate that 1,25(OH)2D3 is an immunoregulatory hormone
TL;DR: The observation that MoAb against the receptor for EGF is cytostatic rather than cytocidal in vitro against A431 cells, yet completely prevents tumor growth in vivo, suggests that some host animal responses also may be involved in the antitumor effect.
TL;DR: A nerve growth factor (NGF) receptor interactive monoclonal antibody (192-IgG) which enhances beta-NGF binding to PC12 cells has been produced and implicate the slow receptor as the mediator of the biological response.
Journal Article•
TL;DR: The use of a clone-specific activating monoclonal antibody at nanogram amounts to activate a cloned helper T cell should allow a detailed characterization of T cell activation via antigen receptor cross-linking.
Abstract: By using as an experimental system the induction of growth of a cloned, antigen:Ia-reactive helper T cell line by an antigen receptor-specific monoclonal antibody, we demonstrated that growth requires two essential co-factors, exogenously produced IL 1 and endogenously produced IL 2. The primary role of the IL 1 is in the expression of receptors on the T cell surface for IL 2, rather than for promoting the synthesis of IL 2. The use of a clone-specific activating monoclonal antibody at nanogram amounts to activate a cloned helper T cell should allow a detailed characterization of T cell activation via antigen receptor cross-linking.
TL;DR: The cDNA for the receptor that mediates the endocytosis and transcellular transport of IgA and IgM across many glandular epithelia into external secretions is cloned and sequenced.
Abstract: We have cloned and sequenced cDNA for the receptor that mediates the endocytosis and transcellular transport of IgA and IgM across many glandular epithelia into external secretions. This receptor contains five extracellular domains which are strikingly homologous to each other and to immunoglobulin variable regions.
TL;DR: A simple theoretical approach is outlined for calculating differences in the free energy of binding of related ligand-receptor pairs.
TL;DR: The findings demonstrate that antigen-induced proliferation is mediated through an autocrine pathway involving endogenous IL-2 production, release, and subsequent binding to IL-3-Ti receptor cross-linking.
Abstract: Human T-cell clones and anti-T-cell-receptor antibodies (clonotypic) directed at surface receptors for antigen (T3-Ti molecular complex) as well as anti-interleukin 2 (IL-2) and anti-IL-2-receptor antibodies were utilized to investigate the mechanism by which alloantigens or antigen plus self-major histocompatibility complex (MHC) (i.e., physiologic ligand) trigger specific clonal proliferation. Soluble or Sepharose-bound anti-Ti monoclonal antibodies, like physiologic ligand, enhanced proliferative responses to purified IL-2 by inducing a 6-fold increase in surface IL-2 receptor expression. In contrast, only Sepharose-bound anti-Ti or physiologic ligand triggered endogenous clonal IL-2 production and resulted in subsequent proliferation. The latter was blocked by antibodies directed at either the IL-2 receptor or IL-2 itself. These results suggest that induction of IL-2 receptor expression but not IL-2 release occurs in the absence of T3-Ti receptor cross-linking. Perhaps more importantly, the findings demonstrate that antigen-induced proliferation is mediated through an autocrine pathway involving endogenous IL-2 production, release, and subsequent binding to IL-2 receptors.
TL;DR: A procedure has been developed for the iodination of human transforming growth factor-beta (TGF-beta) with full retention of biological activity using the iodinated peptide, saturable receptors have been found on normal rat kidney fibroblasts, a cell line that will grow in soft agar in the presence of TGFs but not in their absence.