Porcine dynorphin A (1-13) is a potent, endogenous κ opioid receptor agonist and is antinociceptive at physiological concentrations. Exposure to dynorphin A (1-13) causes acute increases in [Ca2+]i in individual neurons similar to increases seen with acute NMDA treatment.

Hepatitis B Virus Receptor Binding Fragment

BAM-12P, an endogenous opioid peptide, is a novel pro-Met-enkephalin. BAM-12P can activate human κ-opioid receptor (hKOR) with an EC50 of 101 nM and a pEC50 of 6.99. BAM-12P is a ligand for CXCR7 with an EC50 of 175 nM.