Physalaemin, a non-mammalian tachykinin, binds selectively to neurokinin-1 (NK1) receptor with high affinity. IC50 & Target: Neurokinin-1 (NK1) receptor^[1] In Vitro: Physalaemin (PHY), an undecapeptide with the sequence pGlu-Ala-Asp-Pro-Asn-Lys-Phe-Tyr-Gly-Leu-Met-NH2, is a member of the tachykinin family of neuropeptides. PHY is very close to the mammalian tachykinin substance P (SP) in its function and chemical composition, and SP is well studied and characterized^[1]. Physalaemin is a bradykinin potentiating peptide (BPP-5a)^[2].