UNIPROT:P01189 - FACTA Search

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Query: UNIPROT:P01189 (beta-endorphin)
21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two hypophyseal lipolytic peptides, adrenocorticotropin (ACTH) and beta-melanocyte-stimulating hormone (beta-MSH), and the extrhypophyseal lipolytic peptide IIF, were compared with regard to their effects on free fatty acid production and 3',5'-cyclic adenosine monophosphate (cAMP) concentration in isolated rabbit and rat adipose tissue, and on adenylate cyclase activity in the tissue homogenates. ACTH at concentrations of 0.01 mug/ml or more increased lipolysis and cAMP levels in both tissues. beta-MSH at concentrations of 0.001 mug/ml or more increased lipolysis and cAMP in the rabbit tissue, but a concentration of 10 mug/ml did not stimulate lipolysis and did not alter nucleotide concentration in the rat tissue. Peptide IIF at 0.01 mug/ml or more stimulated lipolysis in rabbit adipose tissue and caused an accumulation of cAMP. A concentration of 100 mug/ml failed to stimulate free fatty acid production in the rat tissue and the cAMP level was also unaffected. In a medium containing 7.6 mEq/l of Mg++ and no Ca++, ACTH at 0.1 mug/ml or more stimulated adenylate cyclase activity in both rabbit and rat adipose homogenates by 6- to 12-fold. This effect was inhibited when Mg++ was replaced by Ca++, Na+ or K+. beta-MSH stimulated adenylate cyclase in rabbit, but not in rat, adipose homogenate in Mg++-containing incubation midium; again, the effect on rabbit adenylate cyclase was suppressed when Mg++ was replaced by Ca++, Na+ or K+. Peptide IIF failed to influence adenylate cyclase in the rabbit tissue homogenate in the Mg++-containing, Ca++-free medium; but when the medium contained 7.6 mEq/l of Ca++ in place of Mg++, 0.1 mug/ml or more of IIF caused a 4- to 15-fold increase in cyclase activity. IIF did not affect cyclase in the rat tissue homogenate in the presence or absence of Ca++. The data are consistent with the conclusion that extrahypophyseal lipolytic peptide IIF, as well as hypophyseal peptides ACTH and beta-MSH, accelerates lipolysis in susceptible adipocytes by stimulating adenylate cyclase to produce cAMP. The effect of IIF on cyclase requires the presence of exogenous Ca++; that of ACTH and beta-MSH requires exogenous Mg++.
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PMID:Effects of choroid plexus peptide IIF on adenylate cyclase and 3',5'-cyclic adenosine monophosphate in adipose tissue. 17 24

We have obtained direct evidence that shows the cellular formation and subsequent release of a potent inhibitor (feedback regulator) of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] by adipocytes, upon stimulation with epinephrine. The appearance of such a feedback regulator in adipocytes preceded its release into the medium. During a 30 min incubation, intracellular regulator levels rose rapidly and reached 39-61 units/g of adipocyte at 10 min. Release of inhibitor into the medium increased slowly and was 11-16 units/g of adipocyte at 10 min. Upon continued incubation, the cells at 30 min contained 30-41 units/g of ingibitor, slightly less than the content at 30 min; meanwhile, the medium content rose more than 3-fold. The inhibitor from both locations appeared to have the same characteristics, judging from the purification procedures and the biological activities on hormone-stimulated adenylate cyclase. Adenylate cyclase was inhibited by the feedback regulator in vitro when either epinephrine, corticotropin (ACTH), or glucagon was used as activator. The site of action of this inhibitor is therefore most likely beyond the specific hormone receptors. A new in vitro action of insulin has been found. Insulin, 50-500 microunits/ml, inhibited the formation and release of this factor from isolated rat or hamster adipocytes by 29-81% after these cells were stimulated by hormones that raise intracellular adenosine 3':5'-cyclic monophosphate. This factor enhaced the effect of insulin in lowering the adenosine 3':5'-cyclic monophosphate levels in fresh rat adipocytes. A reduced formation of such a factor may modify the metabolic events in adipocytes, and some as yet unexplained effects of insulin could therefore be linked to the metabolic effects of this factor.
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PMID:Cellular levels of feedback regulator of adenylate cyclase and the effect of epinephrine and insulin. 17 73

Isoproterenol, corticotropin (ACTH), and triodothyronine immobilized on glass and Sepharose beads by diazotization procedures have been shown to interact with cultured tumor cells of "target tissue" origin. Cells used were rat glioma cells (C6), rat adrenal tumor cells (Y-1), and rat pituitary tumor cells (GH3). The rat glioma cells bound principally to immobilized isoproterenol, whereas the rat adrenal tumor cells bound to immobilized corticotropin, and rat pituitary tumor cells bound to immobilized triiodothyronine. Binding was inhibited by preincubation of the cells in soluble drug or hormone. With C6 cells there was a positive correlation between adenylate cyclase [ATP pyrophosphate-lyase (cyclizing, EC 4.6.1.1] stimulation and the degree of binding to the immobilized isoproterenol. Norepinephrine, bound through the ethanolamine side chain via an amide linkage, did not bind cells, demonstrating specific structural requirements for drug-cell interactions. HeLa cells were shown to bind tightly to diphtheria toxin coupled to Sepharose beads via an amide bond. This binding was inhibited by prior incubation of the Sepharose toxin with purified antitoxin. Toxin bound to Sepharose via an azo bond did not bind cells. These data suggest that the cell affinities are due to cell surface receptors interacting with the immobilized drugs and hormones, and that the observed affinities possibly reflect the relative receptor complement of these cells.
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PMID:Affinity isolation of cultured tumor cells by means of drugs and hormones covalently bound to glass and Sepharose beads. 18 May 34

Adenylate cyclase activity in rabbit adipocyte plasma membranes was studied with special reference to the effects of adrenalectomy and administration of cortisol in vivo. Adrenalectomy was accompanied by an increase in adenylate cyclase activity during basal conditions; cortisol (5 mg/kg body wt., intramuscularly) partly prevents this effect of adrenalectomy. The response of adenylate cyclase to corticotropin, epinephrine and norepinephrine stimulation was higher in the adrenalectomized rabbit than in the sham operated animal. Our in vitro results were in agreement with the striking fat mobilization observed in rabbit plasma after adrenalectomy and with the hypolipemic effects of cortisol we had previously observed in both normal and adrenalectomized rabbit.
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PMID:[The effects of adrenalectomy and of hydrocortisone administration on adenylate cyclase activity in rabbit adipose cells (author's transl)]. 18 31

Steroidogenesis by Y-1 adrenal tumor cells in culture is stimulated by ATP, adenyl-5'-yl imidodiphosphate (App(NH)), adenosine 5'(beta, alpha-methylene)triphosphate (App(CH2)p), ADP, AMP, NAD, FAD, and adenosine but not by adenine or other nucleoside triphosphates. ATP, App(NH)p, App(CH2)p, and adenosine are active in the micromolar range. Like adrenocorticotropic hormone (ACTH), the onset of stimulation is immediate and occurs to the same extent. Also active are 2'- and 5'-deoxyadenosine and 2-chloroadenosine whereas adenine xyloside, L-riboside, or arabinoside have very low activity. Stimulation is accompanied by rounding of the cells. Dipyridamole, an inhibitor of adenosine transport, increased the response to low concentrations of adenosine, suggesting that adenosine acts externally. Stimulation of steroidogenesis by adenosine or phosphorylated adenosine compounds fails to occur in the presence of crystalline adenosine deaminase, and the effect of the enzyme on adenosine, ATP, or NAD stimulation is reversed by the competitive inhibitor erythro-9-[3-(nonane-2-ol)]adenine. This suggests that the enzyme acts specifically on adenosine and a requirement for the conversion of the above compounds to adenosine seems probable. The inhibition of cAMP effects by adenosine deaminase suggests that some of its effects are also mediated by conversion to adenosine. Similar stimulation is seen in I-10 Leydig tumor cells, but an ACTH-resistant mutant of Y-1 cells, called OS-3, is relatively resistant to adenosine. Adenosine and 2-chloroadenosine stimulate adenylate cyclase in membranes from Y-1 and I-10 cells at concentrations slightly greater than are effective for steroidogenesis. Other nucleosides are ineffective. Like the NH2-terminal 24 residues of adrenocorticotropic hormone (1-24 ACTH), the adenosine effect in Y-1 membranes is rapid and is on the Vmax intercept (versus ATP) and not on the Km. In contrast to steroidogenesis, adenosine is only a partial agonist for adenylate cyclase. It effect occurs in the presence of ITP, GTP, or guanyl-5'-yl imidodiphosphate (Gpp(NH)p). Theophylline inhibits adenosine-stimulated steroidogenesis. Inhibition of adenylate cyclase occurs in the same concentration range but is of the mixed type.
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PMID:Activation of steroidogenesis and adenylate cyclase by adenosine in adrenal and Leydig tumor cells. 18 24

The ability of ACTH fragments and of an ACTH analogue [9-tryptophan(o-nitrophenylsulfenyl)] corticotropin-(1-24)-tetracosapeptide[Trp-(Nps)9 ACTH1-24] to stimulate adenylate cyclase in bovine adrenal cortex membranes and a crude membrane fraction from rat adrenals has been determined. Partial agonists like Trp (Nps)9 ACTH1-24 displayed intrinsic activity in the rat adrenal preparation only if tested in the presence of 5'-guanylylimidodiphosphate [Gpp(NH)p]. On the other hand, no addition of Gpp(NH)p was necessary to demonstrate intrinsic activity of Trp(Nps)9 ACTH1-24 for bovine adrenal cortex adenylate cyclase. A large decrease (15-fold) of the apparent Km values for ACTH1-24, ACTH1-23 and ACTH1-17 was observed with the rat adrenal preparation when Gpp(NH)p was added. The shift in apparent Km values for ACTH1-24 and ACTH1-23 for the bovine adrenal cortex adenylate cyclase system was small or insignificant when Gpp(NH)p was added. The observations suggest that the hormone receptor facilitates the action of guanylnucleotide sites in the membrane. When guanylnucleotide sites are occupied by Gpp(NH)p even weak interactions of the hormone receptor with e.g. partial agonists are propagated to the catalytic subunits of the adenylate cyclase complex resulting in enhanced activity. The differences in adenylate cyclase activation with hormone fragments or analogues and different target tissues may rather reflect the state of the coupling process involving guanylnucleotide binding sites of the isolated membrane fraction than differences in the receptor itself.
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PMID:Adrenal cortex adenylate cyclase. In vitro acitivity of ACTH fragments and analogues. 18 24

The adenylate cyclase responses of the human GH or ACTH producing pituitary adenomas and ectopic ACTH producing tumors to TRH, LH-RH, biogenic amines, peptides hormones, PGE1 and rat median eminence extract (MEE) have been examined. Out of 4 GH producing pituitary adenomas obtained from patients with active acromegaly at hypophysectomy two were stimulated by TRH, two by LH-RH, three by norepinephrine, one by dopamine, four by PGE1 and none by serotonin. Glucagon stimulated the adenylate cyclase in one of three and MEE in both of two tested. The positive responses of paradoxical GH release after TRH and/or LH-RH before surgery in these patients coincidentally related to the response of adenylate cyclase of each pituitary adenoma. There seems, however, to be no consistent correlation between the adenylate cyclase responses to biogenic amines and the GH release after L-Dopa or 5-hydroxytroptophan tested. The adenylate cyclase of a pituitary adenoma from case of Cushing's disease was stimulated by LH-RH, norepinephrine glucagon and MEE but not by TRH. Plasma levels of ACTH, beta-MSH and cortisol increased after LH-RH but not after TRH in this patient before hypophysectomy. The adenylate cyclase of two ectopic ACTH producing tumors (gastric carcinoid and malignant thymoma) was activated by TRH, LH-RH, norepinephrine, epinephrine, serotonin, PGE1 and MEE. These results indicate the presence of multiple hormone receptors in GH or ACTH producing pituitary adenomas and ectopic ACTH producing tumors, and suggest that the paradoxical GH or ACTH release after TRH and/or LH-RH injection in acromegaly and Cushing's syndrome might be caused by an alteration of the cellular membrane receptors of the pituitary adenomas.
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PMID:Adenylate cyclase of GH and ACTH producing tumors of human: activation by non-specific hormones and other bioactive substances. 19 Feb 56

Human peripheral lymphocytes were broken in a Dounce homogenizer and subcellular fractions enriched in plasma membranes or microsomal particles and mitochondria were isolated by centrifugation through a discontinuous sucrose gradient. Various agents that promote cyclic AMP accumulation in intact lymphocytes were compared in their ability to stimulate adenylate cyclase activity in the individual fractions. Plasma-membrane-rich fractions that were essentially free of other subcellular particles as judged by electron microscopy and marker enzyme measurements responded to fluoride, but weakly or not at all to prostaglandin E1 and other prostaglandins. Microsomal and mitochondrial-rich fractions responded markedly to both prostaglandin E1 and fluoride. In some, but not all, experiments phytohaemagglutinin produced a modest increase in enzyme activity in plasma-membrane-rich fractions. Catecholamines, histamine, parathyrin, glucagon and corticotropin produced little or no response. In the absence of theophylline, adenosine (1-10 micronM) stimulated basal enzyme activity, although at higher concentrations the responses to prostaglandin E1 and fluoride were inhibited. GTP (1-100 micronM) and GMP(5-1000 micronM) respectively inhibited or stimulated the response to fluoride, whereas the converse was true with prostaglandin E1.
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PMID:Adenylate cyclase activity in lymphocyte subcellular fractions. Characterization of non-nuclear adenylate cyclase. 19 77

An assessment was made of some of the basic parameters responsible for the modulation of adenylate cyclase activity in a bovine adrenocortical plasma-membrane preparation. When determined at 0.1 mM-ATP, basal adenylate cyclase activity increased with increasing MgCl2 concentrations, whereas in the presence of corticotropin activity was essentially maximal at 10mM-MgCl2; high concentrations (25mM) of MgCl2 inhibited adenylate cyclase activity determined in the presence of both corticotropin and GTP. At all MgCl2 concentrations, corticotropin and GTP activated the enzyme in a synergistic fashion. The magnitude of the stimulation of basal activity produced by corticotropin was a function of Mg2+ concentration, whereas that produced by GTP appeared largely independent of Mg2+ concentration. Adenylate cyclase activity in the bovine adrenal membrane was half-maximally stimulated by corticotropin concentrations in the range 0.3--1.0 nM. The concentration of corticotropin evoking half-maximum response was not significantly affected by raising the free Mg2+ concentration from 0.4 to 4.9 mM, nor by the presence of GTP. In the presence of GTP, high concentrations (over 1 micrometer) of corticotropin inhibited adenylate cyclase activity, although no inhibition was apparent in the absence of guanine nucleotide.
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PMID:Modulation of the response of bovine adrenocortical adenylate cyclase to corticotropin. 20 64

Our results demonstrate that adrenocorticotropin (ACTH)-induced refractoriness occurs in cultured adrenal tumor cells. Cells became 85% refractory to ACTH-induced cyclic AMP formation in 20 min and the effect persisted if the hormone remained in the incubation medium. Refractory cells gradually regained hormone-specific responsiveness within 24 h if cultures were incubated in fresh media containing serum. The observed effect is hormone specific since cyclic AMP could not induce unresponsiveness to ACTH. The addition of ACTH plus inhibitors of protein synthesis partially reversed hormone-specific refractoriness. However, preincubation with cycloheximide or diphtheria toxin led to superinduction of ACTH-induced cyclic AMP formation. These experiments suggest that unresponsiveness, following hormonal activation of adrenal cells, may be related to a decrease in hormone-specific binding sites or to synthesis of an adenylate cyclase inhibitor.
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PMID:Adrenocorticotropin-induced unresponsiveness in cultured adrenal tumor cells. 20 44

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