Schematic model of human vasopressin receptor (V2R) binding with oxytocin (OT), oxytocin extended form (OT-GKR), and arginine vasopressin (AVP).

(A) The front upright view position (side view) of the receptor structure with OT. (B) The top intracellular view (i.e. rotation by 90o out of plane) of OT-GKR inside the OTR binding site.(C) Conformational view of AVP, OT-GKR, and OT and (D) schematic model of human vasopressin V2R binding with AVP, OT-GKR and OT. The amino acid residues in black circles have been proposed as OT docking sites, the red bars represent docking sites of OT-GKR and the green bars represent docking sites of AVP. Amino acid residues are identified by a 1-letter code in Table 1.