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)

The melanotropin (MSH) receptor of mouse B16-F1 melanoma cells was characterized by photoaffinity cross-linking, using a potent alpha-MSH photolabel, [norleucine4, D-phenylalanine7, 1'-(2-nitro-4-azidophenylsulfenyl)-tryptophan9]-alpha-melanotropin (Naps-MSH). Its monoiodinated form, 125I-Naps-MSH, displayed a approximately 6.5-fold higher biological activity than alpha-MSH. Scatchard analysis of the saturation curves with 125I-Naps-MSH revealed approximately 20,000 receptors/B16-F1 cell and an apparent KD of approximately 0.3 nM. Analysis of the cross-linked MSH receptor by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that a photolabeled band of approximately 45 kDa occurs in B16-F1, B16-F10, and Cloudman S91 mouse melanoma, as well as in human D10 and 205 melanoma but not in non-melanoma cells. The labeled 45-kDa protein had an isoelectric point of 4.5-4.9 as determined by two-dimensional gel electrophoresis. Treatment of the labeled 45-kDa protein of B16-F1 cell membranes by neuraminidase shifted the band to approximately 42 kDa. A similar band of about 42 kDa was also observed after receptor labeling of B16-W4 cells, a cell line with a decreased number of terminal N-linked neuraminyl residues. These results indicate that the labeled 45-kDa glycoprotein contains terminal sialic acid residues, explaining the low pI of this protein, and that it is characteristic for melanoma cells and hence part of the MSH receptor.
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PMID:The receptor for alpha-melanotropin of mouse and human melanoma cells. Application of a potent alpha-melanotropin photoaffinity label. 254 92

To determine whether CRH affects adrenal androgen, beta-endorphin (B-E), and ACTH secretion in normal children during sexual maturation, 17-hydroxyprogesterone (17-OHP), androstenedione (D4-A), dehydroepiandrosterone (DHEA), DHEA sulfate (DS), cortisol, B-E, and ACTH were measured after an iv injection of 1 microgram/kg human CRH. Children with premature pubarche were similarly analyzed to establish whether this condition is accompanied by altered hormonal responses to CRH. CRH produced consistent increases in ACTH, B-EP, and cortisol blood levels, which were comparable at all age intervals in all groups. 17-OHP increased after CRH injection, but its response linearly with age. D4-A levels were not influenced, while DHEA and DS levels were only partially influenced by CRH. The stimulated D4-A to 17-OHP ratio increased with sexual maturation, whereas ratios of cortisol to 17-OHP and D4-A to DHEA remained constant. Children with premature pubarche had hormonal responses similar in magnitude to those of prepubertal children of comparable age. In conclusion, an increase in 17,20-desmolase efficiency occurs with postnatal maturation after CRH challenge. Moreover, CRH does not appear to play an important role in premature pubarche.
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PMID:Adrenal steroid, cortisol, adrenocorticotropin, and beta-endorphin responses to human corticotropin-releasing hormone stimulation test in normal children and children with premature pubarche. 255 May 9

Conditioned medium from human placental monolayer cultures (PM) had a marked stimulatory effect on proliferation (3H-thymidine uptake) of human fetal zone adrenal cells in primary monolayer culture, even in the absence of serum. Epidermal growth factor (EGF) and fibroblast growth factor (FGF) also significantly stimulated fetal adrenal cell growth. However, the effects of PM differed from those of EGF and FGF in several respects: 1) maximal response to PM was 2-5 times greater; 2) mitogenic effects of EGF and FGF were suppressed by adrenocorticotropic hormone (ACTH), whereas that of 50% PM was not; 3) PM inhibited ACTH-stimulated steroidogenesis (dehydroepiandrosterone sulfate and cortisol), but EGF and FGF did not. Preliminary characterization studies have indicated that approximately half of the placental growth-promoting activity is heat resistant and sensitive to bacterial proteases, and that 50-60% of the activity is lost after dialysis with membranes having a molecular weight cutoff of 3500. These findings suggest a role for the placenta in the growth and differentiated function of the human fetal adrenal gland.
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PMID:Effect of placental factors on growth and function of the human fetal adrenal in vitro. 256 Apr 4

Somatostatin, morphine, and opioids inhibit transmitter release at intact neuromuscular junctions between ciliary ganglion neurons and the choroidal smooth muscle of the chick eye. Somatostatin and morphine, however, have no effect on release from terminals on the striated muscle target of the ciliary ganglion, the iris. In neuronal terminals of both the choroid and the iris, a high-affinity Na+-dependent choline uptake-mediated ACh synthesis is present at hatching. Both tissues exhibit a basal release of 3H-ACh which is potentiated severalfold during a 5 minute incubation in 55 mM K+ Tyrodes. Fifty percent of the basal release and 100% of the stimulated release are Ca2+ dependent and probably mediated through N-like voltage-dependent Ca2+ channels. Co-incubation of the choroid with 10 microM morphine sulfate blocks approximately 90% of the stimulated release. The same effect is seen with 100 nM somatostatin, 10 microM dynorphin, and 100 microM met-enkephalin arginine phenylalanine. Preincubation of the excised choroid with pertussis toxin (200 ng/ml) reverses the inhibitory effects of both morphine and somatostatin. In contrast, 3H-ACh release from terminals in the striated iris is not affected by either morphine or somatostatin at micromolar levels. These results suggest that both opiate and somatostatin receptors are present in the choroid target and that they may act through a final common pathway to modulate ACh release via G proteins. Second messengers such as cyclic AMP or diacylglycerol do not appear to mediate these effects; neither increasing cAMP levels in terminals nor activation of protein kinase C affects evoked release or its inhibition by morphine or other neuromodulators. It is unclear whether endogenous neuromodulation occurs in this system, although somatostatin-like immunoreactivity can be demonstrated in terminals of choroid neurons.
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PMID:Opiate and peptide inhibition of transmitter release in parasympathetic nerve terminals. 256 61

An immunoblotting method to detect low-molecular-weight peptides with monoclonal antibodies that normally fail to demonstrate immunoreactivity using conventional blotting techniques is described. Detection of neurophysin, insulin, calcitonin, vasopressin, and beta-endorphin electroblotted on nitrocellulose membranes was optimized after introducing four modifications into the conventional procedure. These include renaturing the gels after sodium dodecyl sulfate electrophoresis, electroblotting the renatured gels in basic transfer buffer, fixing and/or heating the blots, and using avidin/alkaline phosphatase conjugates for antigen/antibody detection. This technique likely enables the denatured peptides to regain their native conformation and, therefore, restores antigenicity and recognition by highly structural specific monoclonal antibodies. Although the most dramatic improvement with this technique is with monoclonal antibodies, a modest improvement in sensitivity can be obtained when immunoblots are probed with polyclonal antibodies. The high resolution of this system will be useful in probing blots of partial proteolytic digests of proteins with both monoclonal and polyclonal antibodies.
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PMID:Detection of low-molecular-weight polypeptides on nitrocellulose with monoclonal antibodies. 269 85

Receptors for alpha-melanocyte-stimulating hormone (alpha-MSH) on human malignant melanoma cell lines were investigated with a specific binding assay and characterized with structural analogues of alpha-MSH and adrenocorticotropic hormone and by photoaffinity cross-linking of the hormone-receptor complex. Specific binding of high-performance liquid chromatography-purified, monoiodinated alpha-MSH in the presence of 1 mM 1,10-phenanthroline as protease inhibitor was highest after a 2-h incubation at 37 degrees C. The nonspecific binding was less than 20% and dissociation of the ligand-receptor complex was relatively slow. Ten out of 12 human cell lines showed specific binding sites for alpha-MSH with Kp values ranging from 0.195 to 2.87 nM and the sites/cell being approximately 400 to approximately 1600. Virtually identical results were obtained in an assay where the cells remained attached to the culture dishes during the entire experiment. The study of hormone analogues with the D10 cell line showed that oxidized alpha-MSH had an approximately 40-fold lower affinity than alpha-MSH whereas [Nle4,D-Phe7]-alpha-MSH displayed a threefold and the adrenocorticotropic hormone fragments (1-17) and (1-24) a 20- and 8-fold higher affinity. Cross-linking of the alpha-MSH-receptor complex of three cell lines using monoiodinated [Nle4,D-Phe7,Trp(2-nitro-4-azidophenylsulfenyl)9]-alpha-MSH as photoaffinity label revealed a major Mr 45,000 protein band on sodium dodecyl sulfate-polyacrylamide gels, analogous to the MSH receptor of mouse B16 melanoma cells.
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PMID:Characterization of receptors for alpha-melanocyte-stimulating hormone on human melanoma cells. 280 81

This report presents a technique for recovery of mouse forebrain proteins from two-dimensional sodium dodecyl sulfate-polyacrylamide gels for subsequent primary structure determination. Proteins were visualized by Coomassie staining or salt precipitation and manually cut out of the gel. Excised spots were minced and loaded into an empty precolumn of a reversed-phase high-performance liquid chromatography system. Purified protein was extruded from a gel matrix by pressurized liquid, then separated from gel contaminants by reversed-phase gradient elution, and finally collected in siliconized tubes or on polybrene-coated filter disks for gas-phase sequencing. Several mouse and rat forebrain proteins were purified by this method and sequenced. Three previously unidentified mouse brain proteins with molecular weights of 4,000, 12,000, and 18,500 were partially sequenced and three hemoglobin fragments were structurally identified and mapped. Ribonuclease A, myoglobin, adrenocorticotropin, and bovine somatotropin were also subjected to two-dimensional (2-D) analysis and partially sequenced. Recovery values of 27-95% were obtained for extruded 14C-labeled ribonuclease, carbonic anhydrase, and bovine serum albumin out of sodium dodecyl sulfate-polyacrylamide gel electrophoretic gels. Losses resulting from the multiple handling steps of a 2-D gel separation process were also investigated. Recoveries of 12-17%, as determined by sequencing signals, were achieved. These latter recovery values reflect overall losses incurred in gel-focusing, gel-sizing, staining, destaining, high-pressure liquid extrusion, and N-terminal blockage. This work demonstrates that an array of protein spots can be systematically identified or defined by partial sequencing after high-pressure liquid extrusion from a 2-D gel matrix.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Isolation and sequence analysis of proteins from mouse forebrain using two-dimensional gel electrophoresis coupled to high-pressure liquid extrusion. 281 64

The roles of human low density lipoprotein (LDL)- cholesterol and high density lipoprotein (HDL)- cholesterol on adrenal steroidogenesis were investigated using cultured human adult and fetal adrenocortical cells and the findings were then compared to those obtained with bovine adrenocortical cells. The secretion of cortisol in both human and bovine adrenocortical cells was dose-dependently increased by the administration of LDL- or HDL-cholesterol in the presence of adrenocorticotropin (ACTH). LDL-cholesterol was utilized to a greater extent than HDL-cholesterol in both human and bovine adrenal steroidogenesis in the presence of ACTH. Exogenous lipoprotein-derived cholesterol was less utilized in human adrenal steroidogenesis than in bovine adrenal steroidogenesis, compared to the endogenous cholesterol. An increase in the secretion of cortisol and dehydroepi androsterone sulfate (DHEA-S) continued for the 5-day culture period, in the presence of lipoprotein cholesterol and ACTH in both human adult and fetal adrenocortical cells. The secretion of aldosterone increased on the first day of the culture period, then gradually decreased for the 5-day culture period in human adult adrenocortical cells, but not in human fetal adrenocortical cells in the presence of lipoprotein cholesterol and ACTH. These findings demonstrate that exogenous cholesterol utilized in the biosynthesis of steroids is mainly from LDL-cholesterol in both human adult and fetal adrenals and bovine adrenal and the proportion of cholesterol synthesized de novo is significantly larger in the human adult adrenal than in the bovine adrenal.
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PMID:Studies on lipoprotein and adrenal steroidogenesis: I. Roles of low density lipoprotein- and high density lipoprotein-cholesterol in steroid production in cultured human adrenocortical cells. 283 99

To determine whether a low pH intracellular "sorting" step is required to route peptides into secretory granules, the effects of pH altering drugs on the biosynthesis and secretion of peptides by AtT-20 mouse corticotrope tumor cells and rat intermediate pituitary cells were examined. Doses of each drug maintaining normal protein synthesis and cell morphology, while obliterating the intracellular pH gradients detected by acridine orange fluorescence, were experimentally determined. Regions of the cell rich in secretory granules were localized by immunocytochemistry and were found to coincide with organelles with a low internal pH. Biosynthetic labeling experiments were coupled with immunoprecipitation and sodium dodecyl sulfate polyacrylamide gel analyses to examine the biosynthesis and secretion of corticotropin (ACTH(1-39], alpha-melanotropin, ACTH(18-39), beta-endorphin, gamma-melanotropin, alpha-amidated joining peptide, and the NH2-terminal region of pro-ACTH/endorphin. Chloroquine (20-40 microM) and a mixture of NH4Cl and methylamine (2-5 mM each) dissipated pH gradients but had no effect on the synthetic rate of pro-ACTH/endorphin, the extent and rate of precursor processing to smaller peptides, the rate of basal secretion of the various peptides, or the extent to which secretion of each of the peptides could be stimulated by secretagogues. Monensin (0.1-1 microM) had no discernible effect on intracellular pH gradients yet totally blocked proteolytic processing of pro-ACTH/endorphin. Thus, a monensin-blockable step occurs in peptide processing, presumably in the trans Golgi region; however, a low pH chloroquine-sensitive sorting step is not required for processing or for routing peptides to a stable storage form which can be released in response to secretagogues.
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PMID:The role of a low pH intracellular compartment in the processing, storage, and secretion of ACTH and endorphin. 283

Very little has been known of the biochemical function of a human adrenocortical carcinoma cell line, SW-13. In this study, the production of several adrenal steroids and 3', 5'-cyclic adenosine monophosphate (cAMP) were investigated in this cell line. The cells were incubated in L-15 medium containing 0.1% bovine serum albumin with several reagents in an atmosphere of 5% CO2 and 95% air for 2 hours at 37 degrees C. Aldosterone (Ald), corticosterone (B), cortisol (F), dehydroepiandrosterone sulfate (DHEA-S) and cAMP were simultaneously assayed by specific radioimmunoassays in the medium and cells. Significant increases in cAMP production were observed by cholera toxin (10 ng/ml) and forskolin (10 nM), both direct stimulators of adenylate cyclase, in the cAMP concentration without an increase in the steroids. The DHEA-S concentration in the medium was significantly increased by angiotensin-II (10(-7)M), noradrenalin (3 X 10(-5) M), adrenalin (3 X 10(-5) M) or alpha-melanocyte-stimulating hormone (alpha-MSH, 10(-7) M), none of which was associated with cAMP production. Neither adrenocorticotropin (10(-10) M) nor human chorionic gonadotropin (500 mIU/ml) stimulated the release of the steroids or cAMP production. A calcium ionophore, A23187 (10(-7) M), and 12-O-tetradecanoylphorbol-13-acetate (10(-8) M), a direct stimulator of protein kinase C, stimulated the release of DHEA-S, but not those of Ald, B and F. The results suggest that SW-13 retains functioning adenylate cyclase which, however, is not linked with steroidogenesis and that DHEA-S is produced probably by the mechanisms which involve protein kinase C system or calcium ion. This report provides the first demonstration of cAMP and DHEA-S production in SW-13 and suggests that this cell line is potentially useful for investigating the mechanisms of steroidogenesis in the human adrenal cortex.
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PMID:Dehydroepiandrosterone sulfate (DHEA-S) and 3', 5'-cyclic adenosine monophosphate (cAMP) production in a cultured human adrenocortical carcinoma cell line (SW-13). 284 Feb 74


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