Targets vasopressin-oxytocin related receptors. Is more active on fish receptors than on their human counterparts, supporting an evolved role of this conopressin in the envenomation process. Acts as an agonist on zebrafish vasopressin receptors V1a1R (EC(50)=10.6 nM), V1a2R (EC(50)=44.06 nM, partial agonist), V2R (EC(50)=299.2 nM) and oxytocin receptor (EC(50)=353.73 nM, partial agonist). Shows a weaker activity on human receptors AVPR1B (EC(50)=51.92 nM), AVPR1A (EC(50)=123.78 nM), AVPR2 (EC(50)=299.2 nM) and oxytocin (OXTR) receptor (EC(50)=455.66 nM, partial agonist). In vivo, exhibits grooming and scratching behavior in mice, following intracerebral injection. Expressed by the venom gland. The cysteine framework of the conopressin is C-C. Monoisotopic mass. Monoisotopic mass of protein with probable hydroxyPro. Monoisotopic mass of protein with probable gamma-carboxylation. The letter 'K' in the name 'Conopressin-K' proposed by Kumar and colleagues stands for the eighth residue, which differs between conopressins. Belongs to the vasopressin/oxytocin family.