Oxytocin Receptor (OXTR) is a 60 - 70 kDa 7TM G protein-coupled receptor for the peptide hormone Oxytocin. OXTR plays a role in several aspects of reproductive function including uterine contraction, mammary gland proliferation, and milk ejection in the female and erection and ejaculation in the male. It also promotes natriuresis and the development of male aggression and mother/offspring relationships. OXTR can form homo-oligomers and hetero-oligomers with the Vasopressin receptors V1a and V2. Human OXTR shares 92% aa sequence identity with mouse and rat OXTR.