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)

The interaction of the ovarian steroid hormones (estrogen and progesterone) and the polypeptide hormone of posterior pituitary origin (oxytocin) appear to regulate the ovine estrous cycle by controlling production of the uterine luteolytic hormone PGF2 alpha. From our results, it appears that these steroid hormones may control PGF2 alpha release by regulating the availability of receptors for oxytocin in the endometrium, the primary site of PGF2 alpha production. Secondarily the ovarian steroid hormones may also regulate basal endogenous levels of oxytocin in the blood stream which may reinforce the luteolytic release of PGF2 alpha. Similar mechanisms may also be operative during the initiation of parturition in which steroid hormones, OT, and PGF2 alpha appear to play major roles (26). In addition to the known interdependence of steroid hormones and the gonadotropins (FSH, LH, and prolactin) required to initiate follicular growth, ovulation, and CL function, there appears to be a second interdependence required to terminate the ovarian cycle via the uterine luteolytic hormone PGF2 alpha, namely by the interaction between ovarian steroids and the posterior pituitary hormone, OT. Thus for both the initiation and termination of the ovarian cycle, there is evidence of a close interaction between the ovary and brain.
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PMID:Hormone receptor control of prostaglandin F2 alpha secretion by the ovine uterus. 624 81

High-performance liquid chromatography (HPLC) is being used extensively to characterize active polypeptides, precursor processing mechanisms, and cooperative peptide-protein noncovalent complexes in neuroendocrine pathways for neurohypophysial peptide hormones, oxytocin and vasopressin, and the hormone-associated proteins, neurophysins. Reversed-phase and ion-exchange HPLC polypeptide mapping have been used to detect the hormones, associated proteins, and other molecular forms containing these. This mapping has provided a means not only to isolate these molecules when present in micro amounts but also ultimately to identify anatomical sites which contain the neurophysin/hormone molecular pathways and to define the relatedness of polypeptide forms contained in different pathways. Reversed-phase HPLC also has provided a means to study proteolytic precursor processing, both to isolate synthetic and semisynthetic polypeptides prepared for use as substrates in processing reactions and eventually to study the polypeptides and intermediates produced by these reactions. Finally, bioaffinity HPLC is being evaluated as a separatory and analytical tool. The latter includes its use to characterize the noncovalent peptide-protein and protein-protein interactions which occur among the molecular forms of the neurophysin/hormone pathways. These experiments typify the impact of HPLC for both analytical and preparative separations in studies of biologically active peptides and proteins.
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PMID:High-performance liquid chromatography and studies of neurophysin-neurohypophysial hormone pathways. 652 26

Isometric tension responses to neuropeptides were recorded from anococcygeus muscles isolated from male mice. This smooth muscle tissue is innervated by inhibitory nonadrenergic, noncholinergic nerves that resemble, ultrastructurally, the peptidergic neurons of the gastrointestinal tract; the physiological function of the anococcygeus is not known. Slow sustained contractions were produced by oxytocin (0.2-20 nM), [Arg8]vasopressin (0.4-200 nM), and [Arg]-vasotocin (0.4-100 nM); the mouse anococcygeus is, therefore, one of the few examples of nonvascular smooth muscle from male mammals to respond to low concentrations of oxytocin and related peptides. Substance P (0.5-8 microM) caused distinctive, biphasic increases in muscle tone of some, but not all, preparations. Other neuropeptides producing contractions were neurotensin (2-100 microM) and thyrotropin-releasing hormone (2-100 microM); the responses were of similar time course and displayed selective cross-desensitization, suggesting that these two peptides act through a common distinct mechanism. Tetradecapeptide somatostatin (10-80 microM) and its analog urotensin II (0.1-5 microM), a dodecapeptide from the urophysis of the teleost fish Gillichthys mirabilis, produced similar slowly developing relaxations of carbachol-induced tone. Piscine urotensin II, of which there are no reported effects on nonvascular mammalian systems, was 20-50 times more potent than somatostatin, a well-established mammalian hormone. Of the peptides studied, only vasoactive intestinal polypeptide (0.05-1 microM) caused rapid powerful relaxations in low concentrations; this is consistent with its proposed involvement in nonadrenergic, noncholinergic neurotransmission in the mouse anococcygeus.
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PMID:Neuropeptide-induced contraction and relaxation of the mouse anococcygeus muscle. 658 16

Using a combination of in vitro methodology, including cell-free translation, two-dimensional peptide mapping and recombinant DNA techniques, the structure of the precursors of the hypothalamic nonapeptide hormones vasopressin and oxytocin has been elucidated. Both hormone precursors are model cellular polyproteins in that they comprise several different entities within the same polypeptide molecule. In each precursor, the nonapeptide hormone follows immediately the signal peptide and is, in turn, attached to its respective carrier neurophysin. The vasopressin precursor also includes a pituitary glycoprotein at its C-terminus. The posttranslational processing of the precursors to set free the nonapeptide hormones is thus a critical regulatory step, which can in part be simulated in the quasi in vivo system of the Xenopus laevis oocyte. The preprohormones to vasopressin and oxytocin illustrate well the convenience of the in vitro experimental approach in understanding the function of the peptidergic neuron.
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PMID:Vasopressin and oxytocin precursors as model preprohormones. 662 4

The nonapeptide hormone oxytocin-like arginine-vasopressin (AVP) is synthesized as part of a larger precursor polypeptide. The precursor also includes the neurophysin molecule with which the hormone is associated in the neurosecretory granules of the hypothalamo-pituitary tract. A protein of molecular weight (Mr) approximately 20,000 has been isolated from supraoptic nuclei of rat hypothalami which, after tryptic cleavage, released a neurophysin-like molecule of Mr approximately 10,000 and an oligopeptide related to oxytocin. This result was complemented by in vitro translation of bovine hypothalamic mRNA. Among the primary translation products a single polypeptide of Mr approximately 16,500 was shown to contain antigenic determinants recognized by specific antisera against bovine neurophysin I and oxytocin. Here we report the amino acid sequence of the bovine oxytocin-neurophysin I (OT-NpI) precursor which was derived from sequence analysis of the cloned cDNA. As is the case for the bovine arginine-vasopressin-neurophysin II (AVP-NpII) precursor, the signal sequence of the OT-NpI precursor is immediately followed by the nonapeptide hormone which is connected to neurophysin I by a Gly-Lys-Arg sequence. A striking feature of the nucleic acid sequence is the 197-nucleotide long perfect homology with the AVP-NpII precursor mRNA sequence encoding the conserved middle part of neurophysins I and II.
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PMID:Deduced amino acid sequence from the bovine oxytocin-neurophysin I precursor cDNA. 668 26

The nonapeptide hormones arginine vasopressin (AVP) and oxytocin (OT) are synthesized in the hypothalamus together with their carrier proteins, the neurophysins, as common polypeptide precursors. The organization of these precursors has been established by sequence determination of cloned bovine cDNAs encoding prepro-arginine vasopressin-neurophysin II (prepro-AVP-NPII) and prepro-oxytocin-neurophysin I (prepro-OT-NPI). When the mRNA sequences coding for the conserved middle part of the neurophysins were compared, we found that these sequences are not merely similar but identical. The primary structure of the chromosomal genes now determined shows that both genes, which appear to have arisen by a gene duplication, are split into three exons, each encoding a functional domain of the precursor polypeptide. Sequence comparison reveals that the stretch of sequence identity within the two mRNAs is probably the result of a gene conversion encompassing exon B, which encodes the conserved part of the neurophysins, and part of the preceding intron.
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PMID:Recent gene conversion involving bovine vasopressin and oxytocin precursor genes suggested by nucleotide sequence. 670 64

A bovine brain thyrotropin-releasing-factor (thyroliberin) deamidase has been purified 1100-fold to apparent homogeneity. Molecular weight estimates by gel filtration and sodium dodecylsulfate gel electrophoresis indicate that the enzyme consists of a single polypeptide chain of molecular weight of about 62 000-65 000. The enzyme is inactivated by sulfhydryl blocking agents. Serine proteinase inhibitors, phenylmethanesulfonyl fluoride and benzamidine, have no effect. Besides thyroliberin, the enzyme hydrolyzes peptide bonds involving the carboxyl group of proline residues in luliberin, tuftsin, angiotensin II, melanotropin, and neurotensin. Oxytocin, vasopressin, and bradykinin are not cleaved; they are, however, strong competitive inhibitors of thyroliberin deamidation. The specificity studies indicate that the enzyme is a "post-proline cleaving enzyme" which hydrolyzes peptides of the general structure, Yaa-Pro-Xaa, in which Xaa = amino acid, peptide, or amide (not Pro), and Yaa = N-blocked basic amino acid or a peptide sequence in which the C-terminal residue (i.e. the residue prior to Pro) is a basic amino acid such as His, Lys, or Arg. The enzyme is compared to other post-proline cleaving enzymes.
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PMID:Purification and properties of a bovine brain thyrotropin-releasing-factor deamidase. A post-proline cleaving enzyme of limited specificity. 679 65

mRNA from membrane-bound polysomes of bovine hypothalamus was translated in an mRNA-dependent cell-free system from reticulocyte lysate or wheat germ. The translation products were identified by immunoprecipitation with antibodies to either neurophysin II or arginine vasopressin followed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. An immunoreactive polypeptide was obtained with an apparent Mr of 21,000. Sequential immunoprecipitation studies indicated that the Mr 21,000 product is a common precursor to neurophysin II and arginine vasopressin. The specificity of the immunoprecipitation was demonstrated by competition with excess amounts of unlabeled neurophysin II or arginine vasopressin; little or no competition was observed with unlabeled neurophysin II or arginine vasopressin; little or no competition was observed with unlabeled neurophysin I or oxytocin. Processing experiments with microsomal membranes from dog pancreas or tunicamycin-treated ascites tumor cells showed that the Mr 21,000 polypeptide is the prepro form. It was converted to a pro form with Mr 19,000 suggesting a pre sequence of approximately 15 amino acids. The Mr 19,000 polypeptide was coreglycosylated to an apparent Mr of 23,000, indicating that the neurophysin II-arginine vasopressin precursor is a glycopolypeptide.
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PMID:Immunological identification of a common precursor to arginine vasopressin and neurophysin II synthesized by in vitro translation of bovine hypothalamic mRNA. 694 Jan 45

The effect of vasoactive intestinal polypeptide (VIP) on uterine smooth muscle electrical and mechanical activity in non-pregnant estradiol-treated rabbits was investigated using in vivo and in vitro methods. The studies were performed on spontaneous, oxytocin-, carbachol-, and prostaglandin-42 alpha-induced activity. VIP had a dose-related inhibitory effect on both myoelectrical and mechanical activity. The concentration needed for 50% inhibition (ID50) was 2 x 10(-10) mol VIP . 1(-1) (in vivo), an 6 x 10(-8) mol VIP . 1(-1) (in vitro). This inhibition was unaffected by the presence of atropine (10(-5) mol . 1(-1)), propranolol (10(-5)), phentolamine (10(-5)), naloxone (10(-5)), apamin (10(-5)), and tetrodotoxin (10(-5)). These findings indicate that VIP may act via a specific receptor on the smooth muscle and supports the hypothesis that VIP may be a neurotransmitter involved in the local nervous control of uterine smooth muscle activity.
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PMID:Vasoactive intestinal polypeptide (VIP): effect on rabbit uterine smooth muscle in vivo and in vitro. 694 84

Partially purified immunoreactive species extracted from bovine posterior pituitary have been labeled with 125I and analyzed by immunoprecipitation with antineurophysin antibodies followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Under denaturing, but nonreducing conditions, a band of Mr = 80,000 was observed. This band corresponded to immunoreactive species detected by radioimmunoassay after chromatography of unlabeled material on a Sepharose CL-4B gel filtration column run in the presence of 6 M guanidine hydrochloride. Under nondenaturing conditions, this species behaved like molecules with an apparent Mr of 140,000 to 160,000. Electrophoretic analysis of the immunoprecipitated material showed that it contained an immunoreactive, single polypeptide chain of Mr = 80,000. Another immunoreactive species of similar molecular weight was also detected, apparently derived from the first one by peptide bond cleavage yielding two fragments of Mr = 68,000 and 10,000, respectively, held together by disulfide bridges. The Mr = 68,000 fragment had lost immunoprecipitability, although its peptide map was largely homologous to that or Mr = 80,000 polypeptide. The 10,000 piece was shown by radioimmunoassay and peptide analysis to be homologous to neurophysin.
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PMID:Characterization of the 80,000 molecular weight form of neurophysin isolated from bovine neurohypophysis. 726 16


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