title: Specific labelling by [125I]helodermin of high-affinity VIP receptors in rat liver membranes.
abstract: 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.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D013007:Growth Hormone-Releasing Hormone / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins; D008099:Liver / Q000378:metabolism*; D008116:Lizards; D008297:Male; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018005:Receptors, Vasoactive Intestinal Peptide; D012633:Secretin / Q000378:metabolism; D017337:Sermorelin; D013997:Time Factors; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism; D014688:Venoms / Q000378:metabolism*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D010455:Peptides; D011956:Receptors, Cell Surface; D018005:Receptors, Vasoactive Intestinal Peptide; D014688:Venoms; D012633:Secretin; D014660:Vasoactive Intestinal Peptide; D006160:Guanosine Triphosphate; D017337:Sermorelin; C040442:heliodermin; D013007:Growth Hormone-Releasing Hormone; D000262:Adenylyl Cyclases