Oxytocin - Synthesis, Storage, and Release

Synthesis, Storage, and Release

Oxytocin, prepropeptide
Identifiers
Symbols OXT; OT; OT-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
• secretory granule
• terminal button
Biological process • response to amphetamine
• regulation of heart rate
• maternal aggressive behavior
• signal transduction
• elevation of cytosolic calcium ion concentration
• heart development
• female pregnancy
• memory
• grooming behavior
• response to sucrose stimulus
• positive regulation of norepinephrine secretion
• response to activity
• sleep
• positive regulation of prostaglandin secretion
• response to estradiol stimulus
• response to retinoic acid
• response to progesterone stimulus
• response to prostaglandin E stimulus
• 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 stimulus
• 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 stimulus
• 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_000915.2 NM_011025.3
RefSeq (protein) NP_000906.1 NP_035155.1
Location (UCSC) Chr 20:
3.05 – 3.05 Mb		 Chr 2:
130.58 – 130.58 Mb
PubMed search

The oxytocin peptide is synthesized as an inactive precursor protein from the OXT gene. This precursor protein also includes the oxytocin carrier protein neurophysin I. The inactive precursor protein is progressively hydrolyzed into smaller fragments (one of which is neurophysin I) via a series of enzymes. The last hydrolysis that releases the active oxytocin nonapeptide is catalyzed by peptidylglycine alpha-amidating monooxygenase (PAM).

The activity of the PAM enzyme system is dependent upon vitamin C (ascorbate), which is a necessary vitamin cofactor. By chance, sodium ascorbate by itself was found to stimulate the production of oxytocin from ovarian tissue over a range of concentrations in a dose-dependent manner. Many of the same tissues (e.g. ovaries, testes, eyes, adrenals, placenta, thymus, pancreas) where PAM (and oxytocin by default) is found are also known to store higher concentrations of vitamin C.

Read more about this topic:  Oxytocin

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