Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bovine thyroid membranes possess both ADP ribosyltransferase and NAD glycohydrolase activities with the same Km values for NAD and the same pH optima. In intact membranes, the ADP ribosyltransferase is limited in its extent by the amount of available membrane acceptor which can be ADP-ribosylated; in membranes solubilized with lithium diiodosalicylate, an artificial acceptor, L-arginine methyl ester, can be substituted to eliminate this limitation. The product of the ADP ribosyltransferase is a mono-ADP-ribosylated acceptor whether the intact or solubilized membrane provides the enzyme activity and whether membrane or exogenous acceptor, L-arginine methyl ester, is utilized. The intact membranes and the solubilized preparation also have an enzyme activity which can release AMP from the mono-ADP-ribosylated acceptor whether formed by the action of the membrane ADP ribosyltransferase or the A promoter of cholera toxin. The NAD glycohydrolase activity appears to represent the half-reaction of the ADP ribosyltransferase, i.e. an activity measurable substituting water for a membrane acceptor or L-arginine methyl ester. Membranes from functional rat thyroid cells in culture, i.e. cells chronically stimulated by thyrotropin and unresponsive to further additions of thyrotropin, have low ADP-ribosylation but high NAD glycohydrolase activities. In contrast, membranes from nonfunctional rat thyroid cells, i.e. cells unresponsive to thyrotropin, have high ADP-ribosylation and low NAD glycohydrolase activities. NAD hydrolysis by the NAD glycohydrolase activity cannot account for the low ADP-ribosylation activity in membranes from the functioning cells, and its low level of ADP-ribosylation can be eliminated by solubilizing the membranes and substituting an artificial acceptor, L-arginine methyl ester. The ADP ribosyltransferase activity of rat thyroid cell membrane preparations can be enhanced by thyrotropin in a dose-dependent manner but not by insulin, glucagon, hydrocortisone, adrenocorticotropin, or its glycoprotein hormone analog, human chorionic gonadotropin. It is thus suggested (i) that, in analogy to cholera toxin, thyrotropin-stimulated ADP-ribosylation may be important in the regulation of the adenylate cyclase response and (ii) that the level of membrane acceptor available for ADP-ribosylation may relate both to a stable "'activated" state of the adenylate cyclase system in cells chronically stimulated with thyrotropin and/or to a desensitized state with regard to a failure of more thyrotropin to elicit additional functional responses.
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PMID:Thyroid membrane ADP ribosyltransferase activity. Stimulation by thyrotropin and activity in functioning and nonfunctioning rat thyroid cells in culture. 627 80

A radioimmunoassay has been developed for the N-terminal region of human pituitary pro-opiocortin (N-POC), the common precursor protein of ACTH and beta-LPH, using an antiserum which recognizes residues near the gamma-MSH region. The concentrations of greater than 300 ng/l of immunoreactive peptide were determined in unextracted human plasma, the relative molecular mass of the reacting fragments corresponding to a seventy-seven amino acid glycoprotein. The concentrations of immunoreactive N-POC peptides were correlated with those of ACTH in plasma obtained from patients with various disorders of the hypothalamic-pituitary-adrenal axis.
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PMID:Development of a radioimmunoassay for an amino-terminal peptide of pro-opiocortin containing the gamma-MSH region: measurement and characterization in human plasma. 627 26

Pro-opiomelanocortin, the common glycoprotein precursor to adrenocorticotropin and beta-lipotropin, is the most abundant protein synthesized in rat neurointermediate lobes. Dissected rat neurointermediate lobes were incubated in the presence of canavanine, an analog of arginine, to determine (a) whether canavanine could be incorporated into pro-opiomelanocortin molecules and (b) if incorporation occurs, whether there is any effect on the processing mechanism of the prohormone. Preincubation of rat neurointermediate lobes for 16 h in the presence of 10 mM canavanine results in the production of pro-opiomelanocortin molecules in which most, if not all, the arginine residues have been replaced by canavanine. Identification of canavanine-containing pro-opiomelanocortin forms was done by two-dimensional electrophoresis, tryptic and chymotryptic peptide mapping, as well as by analysis, on polyacrylamide gels in the presence of sodium dodecyl sulfate, of the fragments resulting from a partial digestion with chymotrypsin. During pulse-chase experiments, canavanine-containing pro-opiomelanocortin molecules were found to be processed at a much slower rate than the normal precursor forms: after a 2-h chase, conversion of approximately 25% of the analog-containing prophormone was observed compared to 83% of the nonanalog-containing precursors. Moreover, the small proportion of canavanine-containing precursor molecules which had undergone cleavage during the chase yielded atypical large molecular weight peptides. These results indicate that canavanine incorporation into neurointermediate lobe proteins considerably slows down the conversion of pro-opiomelanocortin into its different end products.
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PMID:Incorporation of canavanine into rat pars intermedia proteins inhibits the maturation of pro-opiomelanocortin, the common precursor to adrenocorticotropin and beta-lipotropin. 627 67

The pituitary cell line, AtT-20, synthesizes adrenocorticotropic hormone (ACTH) as a glycoprotein precursor that is cleaved into mature hormones during packaging into secretory granules. The cells also produce an endogenous leukemia virus (MuLV) that is glycosylated after translation similar to the glycosylation of the ACTH precursor. Our evidence suggests that the envelope glycoprotein and some precursor ACTH get to the cell surface in a vesicle different from the mature ACTH secretory granule. Viral glycoproteins and ACTH precursor are released from the cells much sooner after synthesis than mature ACTH. Isolated secretory granules do not contain significant amounts of the envelope glycoprotein or ACTH precursor. Exposing cells to 8Br-cAMP stimulates release of mature ACTH four to five fold, but has little effect on the release of the ACTH precursor or the viral glycoproteins. We propose that the viral glycoproteins and some of the ACTH precursor are transported by a constitutive pathway, while mature ACTH is stored in secretory granules where its release is enhanced by stimulation.
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PMID:Two distinct intracellular pathways transport secretory and membrane glycoproteins to the surface of pituitary tumor cells. 627 13

The intermediate lobe of the rat pituitary gland is a homogeneous population of cells synthesizing and secreting various peptides related to ACTH and lipotropin derived from a common glycoprotein precursor, pro-opiocortin. The release mechanism of beta-endorphin from the pituitary gland has been reported by a few investigators, but the precise mechanism is still unknown. The receptors for a catecholamine present in the intact intermediate lobe of the rat pituitary gland remain functional on the enzymatically dispersed cells which secrete beta-endorphin-like immunoreactivity (beta-EPLI) and synthesize adenosine-3',5'-monophosphate (cAMP). Stimulation of beta-adrenoceptor with 1-isoproterenol enhances the synthesis of cAMP and accelerates the rate of beta-EPLI release. The ability of beta-adrenergic agonists to enhance the synthesis of cAMP appears to be causally related to the physiological response to beta-adrenergic agonists (i.e. enhanced beta-EPLI release). Phosphodiesterase inhibitors (theophylline, 3-isobutyl-1-methyl xanthine), cAMP analogs (dibutyryl-cAMP, 8-bromo-cAMP) and cholera toxin also increase beta-EPLI release. These findings suggest that cAMP may participate in this beta-EPLI release process. Furthermore, dopamine inhibits basal beta-EPLI release and also diminishes l-isoproterenol stimulated beta-EPLI release.
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PMID:[Mechanism of beta-endorphin release regulation--evaluation using dispersed cells of the pituitary intermediate lobe]. 631 22

The fetal porcine pituitary was investigated by means of ultrastructural immunocytochemistry (1) to identify the first cells synthesizing the adenohypophyseal hormones, (2) to follow their differentiation during fetal development, and (3) to compare their ultrastructural characteristics with those of mature adult cells. The first ACTH-cells, which produced and stored ACTH, beta-LPH, beta-MSH, and alpha- and beta-endorphin in the same granules, were very numerous at day 34 and displayed a uniform morphology. At day 50 and thereafter, until the end of gestation, the ACTH-cells differed in their appearance probably reflecting various stages of differentiation of one cell type. The GH-cells gained rapidly ultrastructural features comparable to those of mature GH-cells. In contrast, in the case of PRL-cells, which appeared only at the end of the gestation period as immature elements containing very small secretory granules, the morphological maturation seemed to take place only after birth. The first cells synthesizing the glycoprotein hormones (LH alpha, LH beta, FSH and TSH) displayed ultrastructural features of immature cells. At day 50, their ultrastructural organization started to show a different pattern. At the end of gestation, the TSH-cells and the gonadotropic cells displayed the ultrastructural features of mature cells.
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PMID:Functional differentiation of the anterior pituitary cells in the fetal pig. An ultrastructural immunocytochemical study. 632 16

Interferon-alpha inducers were previously shown to cause human lymphocyte production of a corticotropin (ACTH)-like peptide. Thyrotropin (TSH) was not produced under these conditions. In contrast, this report shows that a T-cell mitogen (staphylococcal enterotoxin A), which does not induce the ACTH-like peptide, caused human lymphocyte production of an immunoreactive (ir) TSH. Lymphocyte synthesis of the ir TSH was first detectable at 24 hr, peaked at 48 hr, and thereafter declined. NaDodSO4/polyacrylamide gel electrophoresis of intrinsically radiolabeled lymphocyte-derived ir TSH showed radiolabeled peaks at 80, 50, and 26 kilodaltons. These peaks presumably correspond to trimeric, dimeric, and monomeric TSH-like proteins, respectively. Acid treatment and reduction caused the ir TSH to migrate as a 14-kilodalton peak with a 12-kilodalton shoulder in a gel filtration column run in 6 M guanidine . HCl. Thus, the ir TSH seemed to be composed of subunits with molecular masses corresponding to those of the beta and alpha chains of human TSH, respectively. The ir TSH appeared to be glycoprotein because it bound to a concanavalin A affinity column. Taken together these data suggest that in addition to ACTH, human lymphocytes can also produce a TSH-like substance.
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PMID:Human lymphocyte production of immunoreactive thyrotropin. 635 Oct 72

The pituitaries of adult and fetal crab-eating macaques (Macaca fascicularis) have been studied by immunofluorescence using 15 antibodies against most of the known hormones in the adenohypophysis. The antibodies used were first checked on adult pituitaries for their cross-specificity with macaque pituitary hormones. We found five types of endocrine cells reacting positively, according to the biochemical relation of the molecules evidenced with one or more of the antibodies used. The sequential appearance of the various hormones in the cells of the anterior and intermediate lobes was then determined. The first hormones evidenced at day 45 of pregnancy were ACTH, beta-MSH, beta- and gamma-LPH and alpha- and beta-endorphins. alpha-MSH appeared at day 48 and STH at day 51. The glycoprotein hormones, LH, FSH and TSH, appeared at day 57 but the thyrotropes and gonadotropes did not attain their adult characteristics (staining intensity, morphology, density and distribution in the pituitary) until days 71 and 93, respectively. Prolactin was only found beginning at day 93 of pregnancy. The different specificity tests applied to the pituitary of the macaque, as well as to that of other vertebrates, show that the antibodies used have good specificity. A comparison of the dates at which the fetal pituitary gonadotropes appear in the macaque and the results of a developmental study of the external genital organs in that species indicated that the pituitary gonadotropic function is only established after somatic sex differentiation, which would thus probably occur independently.
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PMID:An immunocytological study of the adult crab-eating macaque (Macaca fascicularis) pituitary and its cytological differentiation during fetal life. 676 Feb 94

This paper reports an immunofluorescent study of the pituitary in the fetal pig (Sus scrofa). Fifteen antisera were used against most of the hormones present in the pituitary. Five types of hypophysial endocrine cells were observed in the anterior and intermediate lobes. We determined the sequential appearance of these various cell types in the fetus. The first hormones found at 33 days were ACTH, beta-MSH, beta- and gamma-LPH and alpha- and beta-endorphin; alpha-MSH appeared at 40 days and STH at 45 days. The glycoprotein hormones, LH (45 days), TSH (50 days) and FSH (60 days), appeared between 45 and 60 days. The density and staining of the gonadotropes increased up to 80 days, at which time they reached values similar to those of the adult. Prolactin was not found until 80 days. An anti-LHRH antiserum was used to study LHRH neuron differentiation between 30 and 70 days of pregnancy. The first immunoreactive perikaryons were found at 40 days but the immunoreactive fibers did not reach the median eminence until about 60 days. However, we observed differentiated capillary loops in the palisade layer of the median eminence only in the 70-day fetus. These results when compared with actual data on the differentiation of the reproductive function in the pig fetus permitted us to define an overall pattern of the differentiation and functioning of the fetal neuroendocrine hypothalamo-pituitary-gonadal system in the porcine species. This pattern includes, (i) autodifferentiation and autofunctioning of the gonads and (ii) autodifferentiation of the pituitary with (iii) later assumption by the hypothalamus followed by a phase during which the whole reproductive system functions.
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PMID:Immunocytological study of the chronology of pituitary cytogenesis in the domestic pig (Sus scrofa) with special reference to the functioning of the hypothalamo-pituitary-gonadal axis. 676 Feb 97

It has been previously established that hypophysectomy leads to renal atrophy in rats and that a crude pituitary-derived fraction is effective in restoring kidney weight to the level expected for intact animals of the same body weight. This paper reports that considerable purification of the crude renotropic fraction from ovine pituitaries has been achieved and that the purified fraction is capable of restoring kidney weights of hypophysectomized castrated rats to normal values. For example, after five daily subcutaneous injections (135 micrograms/day) there were significant increases in dry kidney weight and total renal protein and DNA. The pituitary-derived fraction was devoid of somatotropin, contained only trace amounts of corticotropin, gamma-lipotropin, vasopressin, and prolactin, and had only low levels of thyrotropin and follitropin. Daily injections of prolactin, thyrotropin, and follitropin in doses of 20 micrograms each failed to stimulate renal growth in hypophysectomized rats. Thus, it seems highly unlikely that these factors are responsible for the observed renal hyperplasia after treatment with the pituitary fraction. The purified renotropic fraction had an isoelectric pH between 8 and 9. On polyacrylamide gel electrophoresis in the presence of detergent and a reducing agent, the renotropic fraction exhibited two major bands and one minor band with mobilities that corresponded to those of a standard lutropin preparation. The renotropic fraction exhibited considerable crossreactivity with an antiserum directed against the lutropin alpha subunit, suggesting the presence of the common glycoprotein hormone subunit. Moreover, the purified fraction stimulated steroid production by Leydig tumor cells in vitro. It is noteworthy, however, that standard ovine lutropin at 135 micrograms/day failed to exhibit renotropic activity in hypophysectomized castrated rats, although effects were noted at twice that dose. It appears that the renotropic activity represents a pituitary substance that can be separated from lutropin only with difficulty.
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PMID:Partial purification and characterization of a renotropic fraction from ovine pituitaries. 681 57


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