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 biosynthesis of corticotropin (ACTH1--39), beta-endorphin [beta(61--91)-lipotropin] and alpha-melanotropin in the toad intermediate lobe was studied by using immunoprecipitation procedures with antisera specific for these peptides. Intermediate lobes were pulse-incubated with [3H]phenylalanine and then chase-incubated for varying periods; the radioactive proteins were immunoprecipitated. Immunoprecipitates were separated by acidic urea or sodium dodecyl sulfate polyacrylamide gel electrophoresis. Evidence from the pulse-chase and sequential immunoprecipitation studies using antisera to ACTH and beta-endorphin suggests that the toad intermediate lobe synthesizes two common precursors (apparent Mr 32,000 and 29,500) containing both the ACTH and beta-endorphin sequences. These precursors are processed to yield several forms of immunoreactive corticotropin (apparent Mr 23,000, 21,000, 13,000, and 4300), immunoreactive endorphin (apparent Mr 11,700 and 3500), and immunoreactive alpha-melanotropin. The 4300 Mr form of corticotropin and the 11,700 and 3500 Mr forms of endorphins were found to comigrate with synthetic ACTH1--39, beta-lipotropin and beta-endorphin, respectively, on both acidic urea and sodium dodecyl sulfate gels.
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PMID:Immunological evidence for two common precursors to corticotropins, endorphins, and melanotropin in the neurointermediate lobe of the toad pituitary. 21 21

In idiopathic or generalized epilepsy, serum glucose and cholesterol concentrations tend to be low, especially just before the seizure. Glucose tolerance curves are abnormal and variable. The electrolyte balance is disturbed, and epileptics tend to go readily into alkalosis. Serum [Na+] is usually unaffected, but [K+] is normal to low between attacks and increases during and after the seizure. Serum [Cl-] is usually high just before the seizure. Epileptics are generally mildly hypocalcemic, especially in the period before the seizure. Serum urea and nonprotein nitrogen values are low between paroxysms but increase after the seizure. Serum protein concentration is usually normal. Stress, which releases epinephrine and corticotropin, results in high serum citrate concentration, which probably contributes to decreased serum [Ca2+] just before a seizure. In the healthy individual, any increase in serum citrate is accompanied by increasing [Ca2+]. In the rabbit, convulsions can be induced with corticotropin, a result of increased serum citrate concentration coupled with a decrease in [Ca2+]. The net result is severe hypo-ionic-calcemia. A similar phenomenon has been reported in a few humans. Administration of insulin causes serum citrate concentrations to decrease. Apparently, the dynamic system that controls glucose and lipid metabolism, and thus electrolyte balance, through the hormones epinephrine, corticotropin, insulin, glucagon, calcitonin, and parathormone, is abnormal in the epileptic.
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PMID:Clinical biochemistry of epilepsy. I. Nature of the disease and a review of the chemical findings in epilepsy. 22 Nov 36

The neurointermediate lobes of dark adapted toads, Xenopus laevis, were incubated for 30 min in [3H]arginine, [3H]arginine plus [14C]glucosamine, or [3H]glucosamine and then chased for various time periods ranging from 1--3 h. The labeled polypeptides synthesized and secreted by the lobes were analyzed by acid-urea polyacrylamide gel electrophoresis. A glycosylated ACTH-endorphin precursor (32,000 mol wt) was synthesized during the pulse and identified by immunoprecipitation by ACTH-(11--24) antiserum. During the chase, this precursor was processed to various glycopeptides and peptides, including ACTH, beta-lipotropin, and alpha-MSH, which were subsequently secreted into the medium. An immunoprecipitable ACTH-related glycoprotein (approximately 150,000 mol wt) and other nonimmunoprecipitable glycoproteins (approximately 80,000--100,000 mol wt) were also synthesized and secreted by the neurointermediate lobe. The secretion of these glycoproteins and peptides was inhibited by dopamine. The significance of glycosylation of the precursor for the biosynthesis, processing, and secretion of the ACTH, beta-lipotropin-, and MSH-related peptides was examined by using a specific inhibitor of glycosylation, tunicamycin. Tunicamycin treatment did not affect the synthesis of the 32,000 mol wt ACTH-endorphin precursor but did prevent its glycosylation. The absence of carbohydrate on the precursor resulted in its rapid intracellular degradation. Precursors that escaped degradation were processed incompletely, leading to the formation and secretion of an unglycosylated intermediate and various other abnormal peptides. The data indicate that glycosylation of the ACTH-endorphin precursor may not be involved in the processes of intracellular transport, packaging, and secretion per se but, rather, may provide specific conformational stability to the precursor as a signal for directed limited proteolysis.
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PMID:The role of the carbohydrate in the stabilization, processing, and packaging of the glycosylated adrenocorticotropin-endorphin common precursor in toad pituitaries. 22 74

Protein biosynthesis in neurointermediate lobes of mouse pituitaries was investigated using pulse and pulse-chase techniques with [3H]lysine. Electrophoretic analysis of lobe homogenates on acid-urea gels resolved 11 labeled products. One was a large protein which was rapidly synthesized during pulse-incubations and disappeared during chase incubations. Three of the products increased during chase incubations, suggesting a precursor-product mode of biosynthesis for these chasde peptides. One of these three products co-migrated with synthetic alpha-MSH and also corresponds to the major peak of mouse neurointermediate lobe MSH bioactivity and immunoactivity on electrophoretograms. Another case of these peptides has electrophoretic properties similar to those of ACTH.
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PMID:Biosynthesis of MSH and related peptides in the pars intermedia of the mouse: a pulse-chase analysis. 44 80

The neurointermediate lobes of dark-adapted toads Xenopus laevis were incubated for 30 min in [3H]arginine and then "chased" for various time periods. By use of this pulse-chase paradigm there were detected 10 trichloroacetic acid (TCA)-precipitable peptides separated on acid-urea polyacrylamide gels and one TCA-soluble peptide separated by high-voltage electrophoresis (pH 4.9) with melanotropic activity. Each of these peptides had a different degree of melanocyte stimulating hormone (MSH) activity as revealed by the Anolis skin bioassay. Three of these TCA-precipitable peptides comigrated with ACTH, beta-lipotrophin, and alpha-MSH on acid-urea gels. Evidence suggesting a precursor-product mode of biosynthesis of the melanotropic peptides is presented. 7 of the 10 TCA-precipitable peptides and the one TCA-soluble peptide with melanotropic activity were released into the medium. The half-time of release of the TCA-precipitable peptides was about 2 h, whereas the half-time of TCA-soluble peptide release was about 30 min. The release of these peptides was inhibited by 5 X 10(-5) M dopamine. Dopamine inhibition of release did not appear to affect the biosynthesis of the melanotropic peptides, but did appear to enhance the degradation of the newly synthesized TCA-soluble peptide in the tissue. White adaptation of the toads greatly decreased the biosynthesis of all of the TCA-precipitable melanotropic peptides.
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PMID:Biosynthesis, processing, and control of release of melanotropic peptides in the neurointermediate lobe of Xenopus laevis. 89 50

1. Human pre-procorticotropin releasing hormone (CRH) was expressed in E. coli strain TG2 as a fusion protein with beta-galactosidase. 2. A 140 kDa band which corresponded to beta-galactosidase pre-proCRH fusion protein was identified in lysates of TG2 cells harbouring the recombinant plasmid pre-proCRH (10-196) [ph PPC (10-196)] after sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Coomassie Blue staining. The identity of the fusion protein was confirmed by Western blotting and a two-site immunoradiometric assay. 3. Purification of the fusion protein from isolated, washed and solubilized inclusion bodies was achieved by ion-exchange chromatography in the presence of 8 M urea. 4. When comparing the adrenocorticotropin-releasing activity on a molar basis, the potency of the chimeric CRH precursor was 4% of that of synthetic r/h CRH (1-41).
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PMID:Expression of biologically active human pre-procorticotropin releasing hormone in E. coli: characterization and purification. 212 90

A sodium dodecyl sulfate-polyacrylamide gel electrophoresis system which resolves proteins and peptides from Mr 2000 to Mr 200,000 is described. Gradients of polyacrylamide, crosslinker, and glycerol buffered in Tris-phosphate (pH 6.8) are employed. Neither urea nor a stacking gel is required. This system has been used to separate molecules below Mr 3000 which differed by only seven amino acid residues, yet has the capacity to survey masses up to Mr 200,000 on the same gel. Examples are given for separations of myoglobin cyanogen bromide fragments and adrenocorticotropin peptides. Utilizing the same gradient slab gel system in tandem with isoelectric focusing, a two-dimensional separation pattern of mammalian liver cell lysate is shown. A comparison of two different silver stain methods with this system is also given.
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PMID:A nonurea electrophoretic gel system for resolution of polypeptides of Mr 2000 to Mr 200,000. 242 56

Metabolic defects in obese (fa/fa) Zucker rats have previously been shown to be reversed by adrenalectomy; however, hypercorticosteronemia has not been demonstrated. We now report that the total daily excretion of corticosterone and urea nitrogen are significantly greater (P less than 0.01) in obese Zucker rats than in age-matched lean Zucker rats. This excessive excretion of corticosterone is not of autonomous adrenal origin, since dexamethasone treatment (20 micrograms/kg X day) for 2 days induced a proportionate reduction in corticosterone excretion (approximately 50%) in both obese and lean Zucker rats. Corticosterone excretion was further suppressed to levels not different from those in lean rats after 2 days of dexamethasone (40 micrograms/kg X day). Both the peak and total pituitary beta-endorphin secretion in response to an iv bolus of corticotropin-releasing factor (CRF) were diminished in obese Zuckers. The response to CRF in obese Zucker rats was dampened and superimposable on that of dexamethasone-treated lean Zucker rats, suggesting the existence of chronic hypercorticosteronemia as a component of this genetic obesity. These observations provide evidence for a compensatory alteration of the pituitary-adrenal axis. We suggest that corticosterone turnover may be increased in obese Zucker rats.
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PMID:Hypercorticosteronuria and diminished pituitary responsiveness to corticotropin-releasing factor in obese Zucker rats. 293 45

The modulation of pro-opiomelanocortin (POMC) synthesis in Xenopus laevis pituitary intermediate lobe (IL) during background adaptation and the role of dopamine and cAMP in mediating this effect were examined. Neurointermediate lobes (NILs) were pulselabeled in vitro with [3H]arginine and analyzed for POMC synthesis by acid-urea gel electrophoresis. After black background adaptation of the animal (7 days), POMC synthesis increased 5-6-fold, while after white background adaptation (7 days), POMC synthesis decreased by 76%. Dopamine (50 microM) suppressed POMC synthesis in NILs in culture. In the absence of dopamine, POMC synthesis was stimulated. Several experiments were conducted to determine the category of dopamine receptor in the X. laevis IL. A D-2 dopamine receptor agonist inhibited immunoreactive alpha-MSH release from the NIL in a D-2 antagonist-reversible manner. A D-1 receptor agonist or antagonist did not alter the release of immunoreactive alpha-MSH from the NIL. Dopamine (10 microM) inhibited forskolin-stimulated cAMP accumulation. In addition, dopamine inhibition of POMC synthesis in cultured ILs was reversed by 8-Br-cAMP. These studies suggest that white background adaptation results in stimulation of the X. laevis D-2 receptor, which reduces cAMP production and POMC synthesis. Conversely, during black background adaptation the IL D-2 receptor is not stimulated, leading to increased cAMP production and POMC synthesis.
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PMID:Regulation of pro-opiomelanocortin synthesis by dopamine and cAMP in the amphibian pituitary intermediate lobe. 299 Dec 29

Plasma met-enkephalin and leu-enkephalin has been measured in a group of 28 patients with chronic renal failure, to discover whether these opioids are affected by standard haemodialysis and haemofiltration. Met-enkephalin was markedly higher (P less than 0.001) in uraemic patients than in a group of 13 normal subjects, and was directly related to plasma creatinine (r = 0.60; P less than 0.01) and to plasma urea (r = 0.36; P = 0.06). In contrast, leu-enkephalin was suppressed in uraemic patients (P less than 0.001). Met-enkephalin fell slightly but significantly (P less than 0.02) after both haemodialysis and haemofiltration; however, on average it remained at concentrations four times higher than normal. No changes in plasma leu-enkephalin were observed after haemodialysis and haemofiltration. The cause(s) of the altered plasma concentrations of these opioid substances remains to be clarified.
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PMID:Plasma met-enkephalin and leu-enkephalin in chronic renal failure. 311 Jun 77


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