Neurophysin I

Oxytocin/neurophysin I prepropeptide
Identifiers
Symbols	OXT ; OT; OT-NPI; OXT-NPI
External IDs	OMIM: 167050 MGI: 97453 HomoloGene: 55494 GeneCards: OXT Gene
Gene ontology Molecular function • neurohypophyseal hormone activity • oxytocin receptor binding Cellular component • extracellular region • extracellular space • cytosol • secretory granule • terminal bouton Biological process • response to amphetamine • regulation of heart rate • maternal aggressive behavior • signal transduction • positive regulation of cytosolic calcium ion concentration • heart development • female pregnancy • memory • grooming behavior • response to sucrose • positive regulation of norepinephrine secretion • response to activity • sleep • positive regulation of prostaglandin secretion • response to estradiol • response to retinoic acid • response to progesterone • response to prostaglandin E • social behavior • negative regulation of urine volume • positive regulation of renal sodium excretion • response to cocaine • hyperosmotic salinity response • maternal behavior • sperm ejaculation • eating behavior • drinking behavior • response to peptide hormone • response to ether • negative regulation of blood pressure • positive regulation of blood pressure • positive regulation of ossification • positive regulation of female receptivity • positive regulation of synaptic transmission • response to glucocorticoid • response to cAMP • response to electrical stimulus • regulation of sensory perception of pain • positive regulation of synapse assembly • male mating behavior • positive regulation of penile erection • positive regulation of hindgut contraction • negative regulation of gastric acid secretion • positive regulation of uterine smooth muscle contraction Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	5020	18429
Ensembl	ENSG00000101405	ENSMUSG00000027301
UniProt	P01178	P35454
RefSeq (mRNA)	NM_000915	NM_011025
RefSeq (protein)	NP_000906	NP_035155
Location (UCSC)	Chr 20: 3.07 – 3.07 Mb	Chr 2: 130.58 – 130.58 Mb
PubMed search

Neurophysin I is a carrier protein with a size of 10 KDa and containing 90 to 97 aminoacids that is a cleavage product (formed by splitting of a compound molecule into a simpler one) of preprooxyphysin.^[1] It is a neurohypophysial hormone that is transported in vesicles with oxytocin, the other cleavage product, along axons, from magnocellular neurons of the hypothalamus to the posterior lobe of the pituitary. Although it is stored in secretory vesicles with oxytocin and released with oxytocin, its biological action is unclear.

Structure

The amino acid sequence of Neurophysin I is:

NH₂ - Ala - Ala - Pro - Asp - Leu - Asp - Val - Arg - Lys - Cys - Leu - Pro - Cys - Gly - Pro - Gly - Gly - Lys - Gly - Arg - Cys - Phe - Gly - Pro - Asn - Ile - Cys - Cys - Ala - Glu - Glu - Leu - Gly - Cys - Phe - Val - Gly - Thr - Ala - Glu - Ala - Leu - Arg - Cys - Gln - Glu - Glu - Asn - Tyr - Leu - Pro - Ser - Pro - Cys - Gln - Ser - Gly - Gln - Lys - Ala - Cys - Gly - Ser - Gly - Gly - Arg - Cys - Ala - Val - Leu - Gly - Leu - Cys - Cys - Ser - Pro - Asp - Gly - Cys - His - Ala - Asp - Pro - Ala - Cys - Asp - Ala - Glu - Ala - Thr - Phe - Ser - Gln – Arg - OH

(Disulfide bridge: 10-54; 13-27; 21-44; 28-34; 61-73; 67-85; 74-79)

Function

Neurophysins are carrier proteins for oxytocin and vasopressin (ADH). Oxytocin and vasopressin are carried by unique neurophysins from their site of production in the cell bodies of the paraventricular and supraoptic nuclei to their site of release in the axon terminals of the posterior pituitary.

References

1. Rao VV, Löffler C, Battey J, Hansmann I (1992). "The human gene for oxytocin-neurophysin I (OXT) is physically mapped to chromosome 20p13 by in situ hybridization". Cytogenet. Cell Genet. 61 (4): 271–3. doi:10.1159/000133420. PMID 1486803.