Oxytocin

A cyclic nonapeptide hormone studied in receptor structural biology, reproductive physiology, and social neuroscience research.

Molecular Profile

Type
Endogenous nonapeptide (disulfide-bridged, 9 residues)
Molecular formula
C43H66N12O12S2
Molecular weight
1,007.2 Da
CAS number
50-56-6
Amino acids
9
Sequence
CYIQNCPLG-NH2
Modification
Intramolecular disulfide bond between Cys1 and Cys6; C-terminal primary amide.

Mechanism & Target Class

Oxytocin activates OXTR, a rhodopsin-family (class A) GPCR primarily coupled via Gq/11 to phospholipase C-β, which hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP2) into diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3); IP3 triggers Ca²⁺ release from intracellular stores via IP3 receptors while DAG activates protein kinase C. OXTR can also engage Gi/o-family proteins under certain conditions. The high-affinity active state requires Mg²⁺ as a coordinating cofactor and cholesterol at an extrahelical allosteric site between transmembrane helices IV and V. OXTR shows pharmacological cross-reactivity with the closely related vasopressin receptor subtypes (V1aR, V1bR, V2R), a recognized confound in exogenous-administration studies. Structural studies have resolved the role of a single conserved residue acting as a molecular switch governing cation dependence across the oxytocin/vasopressin receptor family.

Storage & Handling

Lyophilized
-20°C (-80°C long term); lyophilized powder typically stable approximately 24 months.
Handling
Aliquot to avoid repeated freeze-thaw cycles; protect from light; maintain sealed and dry conditions.

Primary Database

PubChem CID 439302 ↗

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