sermorelin and heliodermin

Helodermin, a newly isolated peptide from Gila Monster venom, is structurally related to VIP and secretin. When used as radioligand, [125I]helodermin bound rapidly and reversibly to crude rat liver membranes, the dissociation being accelerated by GTP. Competition binding curves of [125I]helodermin and [125I]VIP with unlabelled peptides showed the following order of decreasing affinity: VIP greater than helodermin greater than secretin greater than hpGRF(1-29)-NH2. The shape of binding curves and of concurrent adenylate cyclase activation is compatible with the specific labelling, by [125I]helodermin, of a class of high-affinity VIP receptors that is capable to stimulate adenylate cyclase.

Topics: Adenylyl Cyclases; Animals; Binding, Competitive; Cell Membrane; Enzyme Activation; Growth Hormone-Releasing Hormone; Guanosine Triphosphate; Intercellular Signaling Peptides and Proteins; Liver; Lizards; Male; Peptide Fragments; Peptides; Rats; Receptors, Cell Surface; Receptors, Vasoactive Intestinal Peptide; Secretin; Sermorelin; Time Factors; Vasoactive Intestinal Peptide; Venoms