Immunogen: Synthetic 19 amino acid peptide from 2nd extracellular domain of human Kappa Opioid Receptor. Percent identity with other species by BLAST analysis: Human, Gibbon, Monkey, Marmoset, Dog, Horse, Rabbit (100%); Gorilla, Mouse, Rat, Elephant, Guinea pig (95%); Bat, Bovine, Panda (89%); Opossum (84%).