Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

[35S]Cysteine injected adjacent to the supraoptic nucleus of the rat is rapidly incorporated into a 20,000-dalton protein that, in time, is converted to a 12,000-dalton labeled protein, neurophysin. This putative precursor of neurophysin appears to be synthesized in the supraoptic nucleus and transformed to neurophysin and related peptides during axonal transport to the neurohypophysis.
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PMID:Neurophysin biosynthesis: conversion of a putative precursor during axonal transport. 6 91

The pre- and post-Golgi processing of preprovasopressin and prepro-oxytocin was evaluated by microsequencing for incorporated radiolabel. 35S-Cysteine and 3H-fucose were microinjected into rat supraoptic nuclei (SON), and proteins and peptides related to the biosynthesis of vasopressin (VP) and oxytocin (OT) were isolated at various times from the supraoptic nuclei and neural lobe by employing a one-step procedure of high performance liquid chromatography (HPLC). These proteins and peptides were recognized through their binding to specific antibodies against VP, OT, and rat neurophysins (RNPs), and by their binding to ConA-Sepharose. Two immunoreactive glycoproteins related to VP biosynthesis were recovered from the SON and both contained fucose and had a 35S-cysteine placement consistent with the location of the hormone sequence at the N-terminus. SDS-electrophoresis revealed the major protein form to be 21,000 daltons and the minor protein form to be 19,000 daltons. One nonglycosylated protein of 16,000 daltons related to oxytocin biosynthesis was recovered from the SON, and this protein also had a 35S-cysteine placement consistent with an N-terminal OT sequence. These data provide the first sequential evidence that prior to, or shortly after, packaging in the Golgi the preprohormones of VP and OT have lost their entire leader-peptide structures.
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PMID:Single-step isolation and sequencing of vasopressin and oxytocin precursors. 140 17

The effect of cysteamine injection on the in vivo incorporation of [35S]cysteine into somatostatin-14 (SRIF-14), SRIF-28, arginine vasopressin (AVP), and oxytocin (OXT) in rat hypothalamus was studied. [35S]Cysteine was injected into the third ventricle 1 h, 4 h, or 1 week after cysteamine (300 mg/kg, sc) injection; animals were killed 4 h later. The drug was found to substantially reduce immunoreactive SRIF levels, but not OXT or AVP, 4 h after its injection. Cysteamine also caused large reductions in label incorporation into SRIF-14, SRIF-28, and OXT 1 and 4 h after drug injection. However, [35S]cysteine incorporation into AVP was increased substantially at these time points, while that into acid-precipitable protein was normal. One week after cysteamine injection, label incorporation into all hypothalamic peptides was normal. Cysteine specific activity was also measured after [35S]cysteine injection and was found to be similar in treatment and control groups. The results suggest that cysteamine inhibits the syntheses of SRIF-14, SRIF-28, and OXT and stimulates that of AVP.
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PMID:Effects of cysteamine administration on the in vivo incorporation of [35S]cysteine into somatostatin-14, somatostatin-28, arginine vasopressin, and oxytocin in rat hypothalamus. 287 17

1. The electrophoretic properties of rat posterior pituitary proteins have been compared on starch gel with those of bovine and porcine neurophysins. 2. [(35)S]-Cysteine was injected into the supraoptic nucleus of male rats and 16-24h later the distribution of labelled neural-lobe protein in starch and polyacrylamide gels was determined. In both systems a single major protein component was found to contain more than 80% of the total recovered radioactivity. Between 5 and 10% of the radioactivity was found in a minor component in polyacrylamide gel. 3. In agar, microimmuno-diffusion and -electrophoresis of the rat neural-lobe proteins gave a single arc with neurophysin antiserum, and after starch-gel electrophoresis this arc was shown to be due to the major labelled component. 4. The molecular weights of the rat neural-lobe proteins were estimated by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. The molecular weight of the major labelled component was found to be 12000. 5. It is concluded that the rat neurophysin consists of one major and possibly one minor component.
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PMID:Electrophoretic and immunological characterization of rat neurophysin. 500 54

Biosynthesis, axoplasmic transport, and storage of neurophysin in the amphibian (Rana pipiens) magnocellular peptidergic neurosecretory system were studied, and the results were compared with those reported in mammals. After injection of [35S]cysteine into the preoptic recess, light microscopic autoradiography provides evidence that neurons of the preoptic nucleus (PON) synthesize cysteine-rich proteins. The time course of appearance of these [35S]cysteine-labeled proteins in different regions of the hypothalamo-neurohypophysial system was studied by slab gel autoradiography. [35S]Cysteine-labeled proteins were found in the PON less than 1 hr postinjection, whereas a major labeled protein, tentatively identified as the neurophysin, first appeared in the infundibulum and neural lobe 4 hr after the injection. In addition, the labeled neurophysin persisted in the neural lobe throughout the entire observation period of 5 days. The minimum transport rate for neurophysin was calculated as 0.9 mm/hr (22 mm/day) at 25 degrees C. Two different neurophysins (with isoelectric points (pI) 4.9 +/- 0.1, 4.6 +/- 0.1, and Mr = 23,000, 20,100) may be resolved from the neural lobe extracts by isoelectric focusing and SDS-polyacrylamide gel electrophoresis, respectively. In addition to the neurophysin peaks, two radioactive peaks with pI 5.2 and 5.8 may be detected in the preoptic nucleus and the infundibulum as early as 30 min after [35S]cysteine injection. Preliminary conversion studies suggest a putative precursor role for the pI 5.2 protein. The results indicate that in the amphibian peptidergic neurosecretory system, the synthesis of cysteine-rich neurophysin by the preoptic neurons, the transport through the infundibulum, and the storage in the neural lobe proceed similarily to their mammalian counterparts.
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PMID:Biosynthesis and axoplasmic transport of neurophysins in the hypothalamo-neurohypophysial system of Rana pipiens. 620 23

We have developed small-scale methods for the isolation and biochemical characterization of subcellular fractions from single guinea-pig posterior-pituitary glands. Secretory vesicles and coated microvesicles produced in this way were of similar purity to those isolated from large amounts of tissue by conventional ultracentrifugation. [35S]Cysteine injected into the hypothalamus was found in the soluble contents of secretory vesicles isolated from the neural lobes 24 h later. High-pressure liquid-chromatographic analysis revealed that the radiolabel was incorporated into the expected neurosecretory products (oxytocin, vasopressin and neurophysin) and also into a biosynthetic intermediate in the vasopressin system. The membranes of secretory vesicles were labelled with [3H]choline 24 h after its hypothalamic injection. Little or no [3H]choline could be demonstrated in coated microvesicles at this time, although these structures were labelled 5 days after injection. Stimulating hormone secretion by chronic dehydration produced a significant fall in [3H]choline content of the secretory-vesicle membranes without any transfer of label into coated microvesicles, suggesting that coated microvesicles are not involved in membrane retrieval in the neurohypophysis.
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PMID:Membrane retrieval in the guinea-pig neurohypophysis. Isolation and characterization of secretory vesicles and coated microvesicles after radiolabel incorporation in vivo. 671 33

Sulfhydryl oxidase is a metalloglycoprotein in milk which catalyzes oxidation of thiols to their corresponding disulfides using molecular oxygen as an electron acceptor. Cysteine, peptides, and proteins all serve as substrates for this oxidative activity. Investigation of the various possible active oxygen species suggests that the enzyme-bound forms of singlet oxygen and a hydroperoxy group may be produced during catalysis. However, the possible intermediate superoxide anions or hydroxyl radicals did not appear to be formed. Evidence was obtained for a direct interaction between sulfhydryl oxidase and horseradish peroxidase which results in an enhancement of the thiol oxidative activity. This interaction also induced a change in the peroxidase absorption spectra consistent with formation of the horseradish peroxidase-II form of the enzyme. Stimulation of oxidase activity also was observed in the presence of oxytocin and certain concentrations of oxidized glutathione.
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PMID:Oxygen activation by sulfhydryl oxidase and the enzyme's interaction with peroxidase. 719 33

[35S]Cysteine-labeled putative precursors for vasopressin-associated neurophysin (NP-VP) and oxytocin-associated neurophysin (NP-OT) were isolated from the supraoptic nuclei (SONs) of normal rats. Homozygous Brattleboro rats were deficient in one of these precursors, the NP-VP precursor. Direct support for the hypothesis that OT and its NP- and VP and its NP are synthesized from two separate macromolecular common precursors was obtained by limited proteolysis of the precursors with trypsin and identification of the fragments as NPs, VP, or OT by a number of criteria (14). In this paper, these common precursors designated propressophysin (precursor for NP-VP and arginine VP) and prooxyphysin (precursor for NP-OT and OT) were further characterized. Propressophysin was specifically bound by Concanavalin-A-Sepharose and was eluted by 0.2 M alpha-methyl mannoside, showing that it is glycosylated. In contrast, prooxyphysin does not appear to be glycosylated. Using [3H]fucose as label injected near the SONs, two proteins (mol wt, approximately 10,000) were identified, which appear to be derived from propressophysin, that are rapidly transported to the posterior pituitary of normal rats. These two proteins were absent in homozygous Brattleboro animals. Both propressophysin and prooxyphysin were bound by a NP-Sepharose affinity support. The binding was different from that of arginine VP or OT to NP, since it was independent of pH and was hydrophobic in nature. In addition to prooxyphysin, the SONs of homozygous Brattleboro rats also contained other [35S]cysteine-labeled protein (mol wt, 20,000) composed of a NP-like protein and NP-binding peptides. The tryptic peptides derived from these proteins were very different in their chromatographic (high performance liquid chromatography) properties than the tryptic peptides derived from propressophysin and prooxyphysin. This protein ('X') was not bound by a Concanavalin-A-Sepharose affinity column, although it had chromatographic properties similar to propressophysin on Sephadex G-75.
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PMID:Biosynthesis of vasopressin, oxytocin, and neurophysins: isolation and characterization of two common precursors (propressophysin and prooxyphysin). 742 96

Methodology is described for characterization of the kinetics and equilibria of thiol/disulfide interchange reactions of the disulfide bonds in the neurohypophyseal peptide hormones arginine vasopressin and oxytocin and the related peptides pressinoic acid and tocinoic acid. Thiol/disulfide interchange reaction mixtures are analyzed by reversed-phase high-performance liquid chromatography. The effect of mobile-phase composition and pH on the HPLC capacity factors for the native disulfide and reduced dithiol forms of each peptide was examined. In each case, the capacity factor decreases as the acetonitrile content of the mobile phase increases. For each disulfide/dithiol peptide pair, the capacity factor is larger for the dithiol form of the peptide, indicating that the hydrophobic side chains of the linear peptide are more accessible for interaction with the hydrophobic stationary phase. To illustrate application of the methodology, rate and equilibrium constants are reported for the thiol/disulfide interchange reactions of cysteine with arginine vasopressin at pH 7.0. Cysteine reacts with arginine vasopressin to form two mixed disulfides, which in turn react with another molecule of cysteine to give the dithiol form of arginine vasopressin and cystine. Rate and equilibrium constants were determined for each step by analysis of reaction mixtures by HPLC. The results are compared to rate and equilibrium constants for reaction of cysteine with oxidized glutathione.
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PMID:Characterization of the thiol/disulfide chemistry of neurohypophyseal peptide hormones by high-performance liquid chromatography. 825 69