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)

Estrogen releases into plasma the human oxytocin neurophysin, previously termed the estrogen-stimulated neurophysin. Because oxytocin and its neurophysin are synthesized as part of a common precursor, stimuli which release the hormone should also release neurophysin and vice versa. However, release of oxytocin with its neurophysin has been difficult to demonstrate by immunological assay in humans administered estrogen. Under this condition, the oxytocin immunoreactivity that is released with the oxytocin neurophysin is a novel peptide which is antigenically similar to oxytocin yet is not oxytocin. Co-release of the oxytocin-like peptide with oxytocin neurophysin suggested that the oxytocin-like immunoreactivity may be a partially processed form of oxytocin. To test this hypothesis the synthetic oxytocin precursor intermediates oxytocin-glycine (G), oxytocin-glycine-lysine (GK), and oxytocin-glycine-lysine-arginine (GKR), were tested for cross-reactivity with the various oxytocin antisera used in this laboratory to distinguish the oxytocin-like peptide from oxytocin. Oxytocin-G, but not oxytocin-GK or GKR, showed extensive cross-reactivity with the oxytocin antiserum (Ab 1), which is known to detect the oxytocin-like peptide of human plasma. Plasma from men and rhesus monkeys administered estrogen and from pregnant women was separated by HPLC and oxytocin Ab 1 immunoreactivity was eluted from the column with the same retention time as synthetic oxytocin-G. Estrogen releases an oxytocin precursor intermediate into the circulation of humans and monkeys and may exert an important effect upon posttranslational cleavage of the oxytocin prohormone. These observations suggest a heterogeneity in the intraneuronal posttranslational processing of the oxytocin precursor in estrogen-treated versus nonestrogen-treated primates.
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PMID:An oxytocin precursor intermediate circulates in the plasma of humans and rhesus monkeys administered estrogen. 211 91

Guinea-pig neural lobes contain appreciable amounts of neurophysin with a glycopeptide extension (NPGP) which may represent a partially processed form of the arginine vasopressin (AVP) precursor. We have now studied the turnover and release of the NPGP component using a combination of in-vivo radiolabel incorporation and high pressure liquid chromatography. Measurement of the neural lobe content of 35S-labelled peptides at various times after hypothalamic injection of [35S]cysteine demonstrated that the oxytocin-related products accumulated more rapidly than the AVP-related products. The relative amounts of [35S]cysteine incorporated into NPGP and the AVP-related neurophysin (NPavp) changed markedly with time after in-vivo labelling. In-vitro incubation of neurosecretory granules prepared from neural lobes 4h after radiolabel injection produced a time- and temperature-dependent conversion of NPGP to NPavp. Incubation at 37 degrees C for 4h produced a 30% decrease in [35S]NPGP with a concomitant increase in [35S]NPavp, whilst there were no changes in the other 35S-labelled components. In-vitro stimulation of radiolabelled neural lobes by 56mM-K+ evoked a Ca++-dependent release of NPGP as well as the other expected neurosecretory components, and the amount of NPGP released reflected its neural lobe content. We conclude that the NPGP component found in guinea-pig neural lobes is a biosynthetic intermediate, most of which is further processed to NPavp. However, some NPGP may also be secreted from the neural lobe in an intact form.
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PMID:Conversion and release of an intermediate in vasopressin-neurophysin biosynthesis in the guinea-pig. 650 61

In addition to oxytocin (OT), vasopressin (AVP) and their respective neurophysins (NPs), another [35S]cysteine incorporating component is present in the guinea pig neurohypophysis. Gel filtration and Con A affinity chromatography revealed that this component was larger than NP and was glycosylated. NP-immunoreactivity was assessed using antisera which distinguish the OT- and AVP-related NPs. Whilst the anti-NP antiserum detected only one component (guinea pig NP), the anti-NP antiserum detected both NP and the glycosylated 35S-labelled component. These results suggest that a significant amount of NP in guinea pig neural lobes bears a glycopeptide extension and represents a partially processed form of the AVP precursor in this species.
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PMID:Characterisation of an intermediate in neurophysin biosynthesis in the guinea pig. 664 47

The sorting of soluble proteins into the regulated secretory pathway (RSP) involves aggregation, but whether an additional sorting domain is also required is not clear. By fusing vasopressin prohormone (proVP) fragments to green fluorescent protein (eGFP) we have determined whether a sorting domain can function independently of the aggregative neurophysin domain. Although eGFP itself can be immunolocalised in the RSP of Neuro2A and AtT20 cells, most of the protein enters the constitutive pathway, and is found in the culture medium. In contrast, the N-terminal 27 residues of proVP promote residence in the RSP. Furthermore, only the processed form of this fusion was secreted when stimulated. We suggest a sorting mechanism based on the recognition of a sorting motif, the efficiency of which is enhanced by neurophysin aggregation.
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PMID:Sorting of the vasopressin prohormone into the regulated secretory pathway. 1086 51