Showing papers on "Receptor published in 1973"
TL;DR: Injection of rabbits with acetylcholine receptor highly purified from the electric organ of Electrophorus electricus emulsified in complete Freund's adjuvant resulted in the production of precipitating antibody to acetylCholine receptor.
Abstract: Injection of rabbits with acetylcholine receptor highly purified from the electric organ of Electrophorus electricus emulsified in complete Freund's adjuvant resulted in the production of precipitating antibody to acetylcholine receptor. After the second injection of antigen, the animals developed the flaccid paralysis and abnormal electromyographs characteristic of neuromuscular blockade. Treatment with the anticholinesterases edrophonium or neostigmine dramatically alleviated the paralysis and the fatigue seen in electromyography.
949 citations
TL;DR: A simple method is reported to detect cooperative interactions in the binding of polypeptide hormones to their membrane receptors, and Insulin receptors on cultured lymphocytes and liver plasma membranes show negative cooperative interactions.
711 citations
TL;DR: It is proposed that receptor transformation is an important step in estrogen action and that a principal role of the hormone is to induce conversion of the receptor protein to a biochemically functional form.
Abstract: The interaction of estradiol with uterine cells involves the association of the hormone with an extranuclear receptor protein, followed by temperature dependent translocation of the resulting complex to the nucleus. During this process, the steroid binding unit of the protein undergoes an alteration, called "receptor transformation," that can be recognized by an increase in its sedimentation rate from 3.8S to 5.2S, and by its acquisition of the ability to bind to isolated uterine nuclei and to alleviate a tissue specific deficiency in the RNA synthesizing capacity of such nuclei. Receptor transformation can be effected in the absence of nuclei by warming uterine cytosol with estradiol. This preparation of transformed complex resembles that extracted from nuclei both in its sedimentation rate (5.3S) and in its ability to bind to uterine nuclei and augment RNA synthesis, properties that are not shown by the native complex. It is proposed that receptor transformation is an important step in estrogen action and that a principal role of the hormone is to induce conversion of the receptor protein to a biochemically functional form.
709 citations
TL;DR: The number of acetylcholine receptors was determined in the neuromuscular junctions of patients with typical myasthenia gravis and in five controls, by means of 1251-labeled α-bungarotoxin binding.
Abstract: The number of acetylcholine receptors was determined in the neuromuscular junctions of eight patients with typical myasthenia gravis and in five controls, by means of (125)1-labeled alpha-bungarotoxin binding. The junctional acetylcholine receptors were reduced in the myasthenic muscles as compared with the controls. This reduction in receptors may account for the defect in neuromuscular transmission in myasthenia gravis.
595 citations
TL;DR: Comparison of the tracks of wild-type and mutant animals responding to gradients of attractants indicates that sensory receptors in the head alone mediate the orientation response and that the direction of orientation is determined by the lateral motion of the head.
Abstract: The nematode Caenorhabditis elegans is attracted by at least four classes of attractants: by cyclic nucleotides, cAMP and cGMP; by anions, Cl(-), Br(-), I(-); by cations, Na(+), Li(+), K(+), Mg(+); and by alkaline pH values. The nematode's behavioral response to gradients of these attractants involves orientation and movement up the gradient, accumulation, and then habitutation. Comparison of the tracks of wild-type and mutant animals responding to gradients of attractants indicates that sensory receptors in the head alone mediate the orientation response and that the direction of orientation is determined by the lateral motion of the head. Therefore, the orientation response is a klinotaxis.
553 citations
TL;DR: Sodium enhances antagonist binding in vitro but decreases agonist binding, a qualitative difference that may be relevant to the divergent pharmacological properties of opiate agonists and antagonists.
Abstract: Receptor binding of opiate agonists and antagonists can be differentiated in vivo and in vitro. Administration of either rapidly elevates stereospecific [(3)H]dihydromorphine binding to mouse brain extracts by 40 to 100 percent, but antagonists are 10 to 1000 times more potent than agonists; as little as 0.02 milligram of naloxone per kilogram of body weight significantly enhances opiate receptor binding. Sodium enhances antagonist binding in vitro but decreases agonist binding, a qualitative difference that may be relevant to the divergent pharmacological properties of opiate agonists and antagonists.
507 citations
TL;DR: Human peripheral lymphocytes were investigated for receptors binding Epstein-Barr virus because of the regular association of this virus with infectious mononucleosis and Burkitt's lymphoma and it was concluded that B lymphocytes, in contrast to T lymphocyte, have receptors for EBV.
Abstract: Human peripheral lymphocytes were investigated for receptors binding Epstein-Barr virus (EBV) because of the regular association of this virus with infectious mononucleosis and Burkitt's lymphoma. This was done by a cytoadherence technique where virus-producing cells, displaying fresh viral determinants in their cytoplasmatic membrane, were mixed with lymphocytes. Unfractionated lymphocytes were found to adhere to these cells in contrast to column-purified T lymphocytes. The specificity of the binding was confirmed by blocking experiments that showed that sera containing high titers of antibodies directed against the virus could partially inhibit the adherence in contrast to low-titer sera. It is concluded that B lymphocytes, in contrast to T lymphocytes, have receptors for EBV. In a second line of experiments it was found that established human lymphoblastoid lines that carry the EBV genome had receptors characteristic for B lymphocytes and did not form T-lymphocyte rosettes. In contrast, a line of known T-lymphocyte origin that did not carry the EBV genome had receptors characteristic for T lymphocytes. EBV-transformed simian lymphoblastoid lines had surface markers indicating a B-lymphocyte origin in contrast to HVS-transformed simian lines that lacked surface immunoglobulin but carried receptors for sheep red blood cells.
498 citations
TL;DR: A stable cell line derived by pleural effusion from a breast cancer patient has been demonstrated to contain significant amounts of 17β-estradiol receptor, which has a Kd equal to 2.5 nm, a sedimentation constant of 4.0 S, and a mechanism capable of transporting the 17 β-ESTradiol into the nucleus.
424 citations
TL;DR: The decrease in insulin receptors in the ob/ob mouse correlates well with the insulin resistance which they exhibit and Scatchard analysis suggests that this decrease in binding is due to a decrease in the number of receptor sites in the membrane of the obese mouse, especially those of higher affinity.
408 citations
TL;DR: The proposed model has several implications for studies of the initial events of mitogenesis in lymphocytes as well as for cell-cell interactions in general.
Abstract: An analysis of the inhibition by concanavalin A of the mobility of lymphocyte surface receptors is used to construct an hypothesis on membrane receptor-cytoplasmic interactions. It is proposed that binding of multivalent lectins alters the interaction of an assembly of colchicine-binding proteins with lectin receptors and other receptors, and reciprocally that the state of the colchicine-binding assembly alters the mobility and distribution of surface receptors on the cell membrane. Observations of the effect of colchicine and related drugs on the inhibition of receptor mobility by concanavalin A lend support to this hypothesis. The proposed model has several implications for studies of the initial events of mitogenesis in lymphocytes as well as for cell-cell interactions in general.
389 citations
TL;DR: Con A shows a greater capacity than succinyl-Con A to agglutinate sheep erythrocytes and to inhibit cap formation by immunoglobulin receptors on spleen cells, and at low concentrations, Con A induced its glycoprotein receptors to form caps, but succ Vinyl A did not induce cap formation.
Abstract: Chemical derivatization of tetrameric concanavalin A (Con A) with succinic anhydride or acetic anhydride converts the protein to a dimeric molecule without altering its carbohydrate-binding specificity. At low concentrations, the dose-response curves for the mitogenic stimulation of mouse spleen cells by native Con A and succinyl-Con A are similar. Above lectin concentrations of 10 μg/ml, however, the response to Con A is diminished, while that for succinyl-Con A does not decrease until much higher doses are reached. We have attributed this difference mainly to the higher rate of cell death induced by the native Con A molecule. Con A also shows a greater capacity than succinyl-Con A to agglutinate sheep erythrocytes and to inhibit cap formation by immunoglobulin receptors on spleen cells. Moreover, at low concentrations, Con A induced its glycoprotein receptors to form caps, but succinyl-Con A did not induce cap formation. Addition of antibodies directed against Con A to succinyl-Con A bound on cells restored the properties of agglutination, inhibition of immunoglobulin receptor cap formation, and induction of cap formation by Con A receptors. Similar results have been obtained for acetyl-Con A. These data suggest that the altered biological activities of succinyl-Con A and acetyl-Con A are attributable to their reduced valence.
TL;DR: The finding of lymphocytes with only one of the two B cell markers suggests that these markers are not uniformly present on all B cells and that depending on the source, one or the other may be deficient.
Abstract: Human lymphocytes from normal peripheral blood, thymus, spleen, thoracic duct, and peripheral lymphocytes from patients with chronic lymphatic leukemia were studied for complement receptor sites (CRL), surface immunoglobulin (SIg), and for the ability to form rosettes with sheep erythrocytes (TRFC). The two B cell markers (CRL and SIg) were found to be in overlapping, but not totally identical populations, whereas cells that were able to form rosettes were found in a totally unrelated population of lymphocytes; TRFC is therefore probably a reliable marker for T cells. In peripheral blood 24% of lymphocytes had SIg, but only half of these were also CRL. Almost all of the non-SIg peripheral blood lymphocytes were TRFC. In the spleen and thoracic duct only a few lymphocytes were observed that had SIg and were not CRL. On the other hand, in two of three spleens studied 10-20% of cells were CRL that did not have SIg. In the thoracic duct all non-CRL that did not have SIg. In the thoracic duct all non-CRL, non-SIg cells were TRFC. In chronic lymphatic leukemia three findings were made: (a) The presence or absence of CRL was independent of the presence or absence of SIg so that in individuals whose cells were non-SIg. CRL were usually plentiful. (b) Leukemic cells were essentially negative for TRFC. (c) Leukemic cells reacted poorly with human C3 compared to mouse C3, EACmo detecting up to 20-fold more CRL than EAChu. This latter finding was in sharp contrast to normal CRL that reacted somewhat preferentially with EAChu. These data suggest that altered surface Ig receptors and complement receptors are present in chronic lymphatic leukemic cells. Since the cells obtained from all leukemic patients tested in this study had either the complement receptor or surface immunoglobulin in a high percentage of their cells and were essentially negative for TRFC, it is strongly suggested that leukemic lymphocytes are of B cell origin. The finding of lymphocytes with only one of the two B cell markers suggests that these markers are not uniformly present on all B cells and that depending on the source, one or the other may be deficient.
TL;DR: The data suggest that the progesterone receptor in the guinea pig uterus is under a double control: a positive control by estrogen, requiring RNA and protein synthesis, and a negative control by progester one, possibly due to an increased inactivation rate.
TL;DR: The binding of triiodothyronine and thyroxine to cellular fractions after incubation with intact cells in serum-free medium and high-affinity, low-capacity binding sites for the hormones were demonstrated in nuclear but not in mitochondrial or cytosol fractions suggest that triiod Timothyronine-Thyroxine interaction with identical nuclear receptors may not be a prerequisite for biologic activity.
Abstract: Triiodothyronine and thyroxine induce a 3-fold increase in the rate of growth of GH1 cells in culture. To study further the action of these hormones, we examined the binding of [125I]triiodothyronine and purified [125I]thyroxine to cellular fractions after incubation with intact cells in serum-free medium. High-affinity, low-capacity binding sites for the hormones were demonstrated in nuclear but not in mitochondrial or cytosol fractions. Chromatographic analysis of the bound nuclear radioactivity from cells incubated with [125I]thyroxine demonstrated 97% thyroxine, 1% iodide, and 1% triiodothyronine. Apparent equilibrium dissociation constants, determined by Scatchard analysis, were 29 pM for triidothyronine and 260 pM for thyroxine. The maximal binding capacity was identical for both hormones, with about 5000 sites per cell nucleus. [125I]Thyroxine binding was competitively inhibited by triiodothyronine. These data suggest that triiodothyronine and thyroxine interact with identical nuclear receptors, and that conversion of thyroxine to triiodothyronine may not be a prerequisite for biologic activity. Similar high-affinity, low-capacity nuclear binding sites were also demonstrated by incubation of [125I]triidothyronine directly with isolated nuclei. Incubation of cells with increasing concentrations of nonradioactive triidothyronine results in a subsequent increase in binding when [125I]triiodothyronine is then incubated directly with isolated nuclei. This result suggests that nuclear receptors are not fixed, but increase after exposure of intact cells to hormone. This increase in nuclear receptor content may result from the transfer of an unstable cytosol receptor to the nucleus.
TL;DR: Insulin interactions with human lymphocytes in established cultures and with isolated peripheral lymphocytes have been studied using 125I-insulin and the lymphocyte receptors show striking similarities to those structures described in fat cell and liver preparations.
TL;DR: Observations indicate that fibroblasts possess receptors for EGF by biological and physicochemical criteria, and suggest that a similar if not identical peptide may be amongst those factors in sera which stimulate cell growth.
Abstract: Epidermal growth factor (EGF) stimulates both DNA and RNA synthesis in contact-inhibited human fibroblasts. Stimulation of DNA synthesis is observed at concentrations as low as 3 pM, is half-maximal at 70 pM, and is maximal at 300 pM EGF. The action of EGF is similar to that of fetal-calf serum, but is distinguished by the time-course of stimulation and by the ability of serum to stimulate further those cells maximally stimulated by EGF. Cells that synthesize DNA in response to physiological concentrations of EGF (10-11 to 10-10 M) are insensitive to physiological concentrations of insulin (10-11 to 10-10 M) and respond only minimally to very high concentrations of this hormone (10-6 M). The biological activity of EGF is paralleled by binding of this peptide to fibroblasts in a specific and saturable manner; the dissociation constant is about 800 pM. The binding of EGF is unaffected by either insulin or cholera toxin. Cholera toxin inhibits the action of both EGF and serum. Suppression of DNA synthesis is observed at 0.02 pM toxin, and is maximal at about 2 pM. Cells treated with cholera toxin at these concentrations appear to be otherwise viable by several criteria. The stimulatory effects of EGF are also inhibited by theophylline and dibutyryl cyclic AMP separately or in combination. These observations indicate that fibroblasts possess receptors for EGF by biological and physicochemical criteria, and suggest that a similar if not identical peptide may be amongst those factors in sera which stimulate cell growth. The possibility is considered that EGF and cholera toxin modulate the ability of a cell to initiate polynucleotide synthesis by way of specific cell-surface interactions which in turn alter the levels of intracellular cyclic AMP.
TL;DR: It will be clear that scientists now working with peptide hormone receptors have appropriated directly methods and technical approaches that were devised by Berson and Yalow for radioimmunoassay for the development ofThis paper describes how the approach has been extended by dozens of laboratories to many other peptide hormones.
Abstract: B ERSON AND YALOW hardly ever worked directly on receptors, but they did make many key contributions that have led to the development of this area. It will be clear that scientists now working with peptide hormone receptors have appropriated directly methods and technical approaches that were devised by Berson and Yalow for radioimmunoassay. Further, Berson and Yalow helped create and formulate concepts and ideas-for example the unity of the peptide hormones-that have led to the swift spread of receptor studies from one hormone to another. In reading further, much of the debt to Berson and Yalow will be obvious, while their other contributions are more subtle but equally important. I shall try to highlight these in the last section of the paper. For a hormone to activate a target tissue, it must first bind to some constituent of the cell. This first step in polypeptide hormone action had been studied indirectly for many years by measuring some effect of the hormone, but it was not until 1969 that this key step was measured directly. In that year two groups. using ““I-ACTH and “‘1-angiotensin, respectively, demonstrated methods that were applicable generally for the direct study of the interaction of peptide hormones and their specific receptors on target cells.’ ’ The approach has been extended by dozens of laboratories to many other peptide hormones (Table I), and an enormous amount of new direct information has been gathered about hormone-receptor interactions including the number of receptor sites per cell. their affinity and specificity, the speed of hormone binding and dissociation, measurements of hormone in plasma and demonstrations of alterations in receptors in association with disease states in animals and man.
TL;DR: Concanavalin A and wheat germ agglutinin are as effective as insulin in enhancing the rate of glucose transport and in inhibiting epinephrine-stimulated lipolysis in isolated adipocytes and their effects are equally apparent in insulin-binding proteins solubilized from membranes, indicating that the plant lectins interact directly with insulin receptors.
Abstract: Concanavalin A and wheat germ agglutinin are as effective as insulin in enhancing the rate of glucose transport and in inhibiting epinephrine-stimulated lipolysis in isolated adipocytes. These lectins, also like insulin, inhibit basal as well as epinephrine-stimulated adenylate cyclase activity of membranes obtained from homogenates of fat cells. Low concentrations of wheat germ agglutinin enhance the specific binding of insulin to receptors of fat cells and liver membranes. Higher concentrations of this plant lectin, as well as of concanavalin A, competitively displace the binding of insulin to receptors in these tissues. These effects are equally apparent in insulin-binding proteins solubilized from membranes, indicating that the plant lectins interact directly with insulin receptors. All of the effects observed with the plant lectins are reversed by simple sugars that bind specifically to these plant proteins. Agarose derivatives of the plant lectins effectively adsorb solubilized insulin-binding proteins, and these can be eluted with buffers containing specific simple sugars. The possible implications of these findings to certain biological properties (mitogenicity) of these lectins and to the mechanism of action of other growth-promoting substances are considered.
TL;DR: It is found that many potent synthetic androgens can bind directly to β protein and to prostate cell nuclei without a metabolic conversion, indicating that the bulkiness and flatness of the steroid molecule play a more important role in receptor binding than the detailed electronic structure at the Δ4 bond of Ring A.
TL;DR: Evidence is presented that these B(12) receptor sites also function as the receptors for the E colicins, and that there is competition between B( 12) and the E Colicins for occupancy of these sites.
Abstract: The first step in the transport of cyanocobalamin (CN-B(12)) by cells of Escherichia coli was shown previously to consist of binding of the B(12) to specific receptor sites located on the outer membrane of the cell envelope. In this paper, evidence is presented that these B(12) receptor sites also function as the receptors for the E colicins, and that there is competition between B(12) and the E colicins for occupancy of these sites. The cell strains used were E. coli KBT001, a methionine/B(12) auxotroph, and B(12) transport mutants derived from strain KBT001. Colicins E1 and E3 inhibited binding of B(12) to the outer membrane B(12) receptor sites, and CN-B(12) protected cells against these colicins. Half-maximal protection was given by CN-B(12) concentrations in the range of 1 to 6 nM, depending upon the colicin concentration used. Colicin E1 competitively inhibited the binding of (57)Co-labeled CN-B(12) to isolated outer membrane particles. Functional colicin E receptor sites were found in cell envelopes from cells of only those strains that possessed intact B(12) receptors. Colicin K did not inhibit the binding of B(12) to the outer membrane receptor sites, and no evidence was found for any identity between the B(12) and colicin K receptors. However, both colicin K and colicin E1 inhibited the secondary phase of B(12) transport, which is believed to consist of the energy-coupled movement of B(12) across the inner membrane.
TL;DR: The data suggest that the cell-free system described here adequately represents some of the early steps in glucocorticoid action, including the number of sites, the high affinity of the interaction, the necessity for activation, and the fact that the receptor must be bound with steroid.
TL;DR: In 15 out of 18 chronic lymphatic leukemia patients, the immune adherence receptor was either partially or completely missing from the peripheral lymphocytes, while the lymphocyte receptor for C3b inactivator-cleaved C3B was retained.
Abstract: In the present study it was shown that normal peripheral lymphocytes have two different complement receptors: one for C3b (the immune adherence receptor) and one for C3b subsequent to its cleavage by C3b inactivator. The two receptors are not cross-reactive and were shown by tests with various antisera to be antigenically distinct. Both the immune adherence receptor and the receptor for C3b inactivator-cleaved C3b were found on normal peripheral lymphocytes and on cultured lymphoblastoid cells. In 15 out of 18 chronic lymphatic leukemia patients, the immune adherence receptor was either partially or completely missing from the peripheral lymphocytes, while the lymphocyte receptor for C3b inactivator-cleaved C3b was retained. Normal erythrocytes, on the other hand, were found to have only the immune adherence receptor. Granulocytes from normal peripheral blood appeared to have only a receptor for C3b and did not have a receptor for C3b inactivator-cleaved C3b.
TL;DR: The results demonstrate a clearcut dissociation between the sites of biosynthesis and metabolism in the kidney and the function of the cortical PGDH might be either to inactive prostaglandins formed in medulla or to protect medullary PG receptors from high levels of circulating prostag landins.
TL;DR: The toxin-receptor equilibrium and the DEAE-filter paper assay provide a convenient method for studying the interaction of receptor with cholinergic ligands.
TL;DR: Two specificity—conferring mechanisms are described which are posited to allow aldosterone occupancy of its appropriate receptor in target tissues.
Abstract: The current hypothesis of the mechanism of action of aldosterone includes an initiating step of binding of the steroid to stereospecific receptor proteins in target tissues. In view of the very low circulating levels of aldosterone relative to other adrenal steroids, there must exist potent specificity—conferring mechanisms to insure appropriate aldosterone occupancy of mineralocorticoid receptors. Two specificity—conferring mechanisms are described which are posited to allow aldosterone occupancy of its appropriate receptor.In vitro, renal aldosterone binding sites are shown to fall into two classes. Those with a higher affinity for aldosterone—Kdlss (37 C)≅ 5X10-10—are termed Type I; those with a lower affinity—Kdiss (37 C)≅ 2.5 X lO-8— Type II. Desoxycorticosterone (DOC) has ∼80% the affinity of aldosterone for both sites. Corticosterone (B) has a high affinity for Type II sites, but less than 2% of the affinity of aldosterone for Type I. From the relative affinities of the three steroids for Type I, t...
TL;DR: Decapsulated intact rat testes are highly sensitive to gonadotrophic stimulation in vitro, responding to HCG concentrations as low as 0.1 ng ml−1 (10−12 M) with synthesis and release of testosterone and to higher concentrations with synthesisand release of cyclic AMP.
Abstract: GONADOTROPHIN receptor sites with high specificity and affinity for luteinizing hormone (LH) and human chorionic gonadotrophin (HCG) have been demonstrated in particulate and soluble interstitial cell fractions of rat testis1–4. Such hormone binding sites have been used in radioligand receptor assays for LH and HCG1,2 and in studies on the structural determinants of gonadotrophin binding to target tissue5–7. Other parameters of gonadotrophin action have been examined during incubation of intact rat testes with HCG by radioimmunoassay of the cyclic AMP and testosterone produced during trophic hormone stimulation in vitro8–11. Decapsulated intact rat testes are highly sensitive to gonadotrophic stimulation in vitro, responding to HCG concentrations as low as 0.1 ng ml−1 (10−12 M) with synthesis and release of testosterone and to higher concentrations with synthesis and release of cyclic AMP10. Release of cyclic AMP during incubation with HCG has been shown to reflect cyclic AMP synthesis by simultaneous measurement of 14C-adenine incorporation and radioimmunoassay of cyclic AMP9,10.
TL;DR: This work has shown that the structure of these molecules, characterized by repeating antigenic determinants, would make it possible for the molecules to establish multiple interactions with the immunoglobulin receptors of the B cells and thus cause their activation.
Abstract: CERTAIN antigens are known to be immunogenic in the absence of thymus-derived (T) lymphocytes1–5. One extreme explanation of this is that all antigens are fundamentally thymus-independent, whereas the contrary view is to deny the experimental evidence for the existence of this type of antigen6. Another explanation for thymus-independency is based on the structure of these molecules, which are characterized by repeating antigenic determinants. This special structure would make it possible for the molecules to establish multiple interactions with the immunoglobulin receptors of the B cells and thus cause their activation7.
TL;DR: The results suggest that nuclear binding of glucocorticoids is due to the association with the nucleus of the cytoplasmic receptor-steroid complex itself and make it unlikely that the receptor acts as a mere carrier for the intracellular transfer of the steroid.