InterPro

Oxytocin and vasopressin are nine-residue, structurally and functionally related neurohypophysial peptide hormones. Oxytocin mediates contraction of the smooth muscle of the uterus and mammary gland, while vasopressin has antidiuretic action on the kidney, and mediates vasoconstriction of the peripheral vessels [PMID: 3147712]. In common with most active peptides, both hormones are synthesised as larger protein precursors that are enzymatically converted to their mature forms. Members of this family are found in birds, fish, reptiles and amphibians (mesotocin, isotocin, valitocin, glumitocin, aspargtocin, vasotocin, seritocin, asvatocin, phasvatocin), in worms (annetocin), octopi (cephalotocin), Locusta migratoria (Migratory locust) (locupressin or neuropeptide F1/F2) and in molluscs (conopressins G and S) [PMID: 7591488].