(Glu8·9) -Helodermin

(Glu8·9) -Helodermin has been isolated from the salivary gland of the Gila monster Heloderma suspectum. It consists of 35 amino acids and shares 53 and 42% homology with human pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP), respectively. It was shown to have high affinity for the mammalian VIP2 receptor and equal potency and efficacy for stimulating cAMP production compared with mammalian VIP and PACAP. Even a helodermin-preferring receptor has been described. Furthermore, immunohistochemical studies, using antibodies that did not cross-react with mammalian VIP or PACAP or other known members of the GLP-1 / VIP / PACAP peptide family suggested the existence of a mammalian homologue to (Glu8·9) -Helodermin distinct from VIP and PACAP.