title: Interaction of synthetic N- and C-terminal fragments of helodermin with rat liver VIP receptors.
abstract: Synthetic helodermin was more potent than natural helodermin (purified from the venom of Gila monster) in activating adenylate cyclase in rat liver membranes. Two possible reasons for this discrepancy were discussed. Comparing adenylate cyclase activation to the binding of 125I-natural helodermin and 125I-VIP in the presence of six synthetic helodermin fragments (1-27, 7-35, 13-35, 17-35, 18-35 and 22-35), we conclude that the effects of both synthetic and natural helodermin were mediated through an interaction with VIP receptors. The C-terminal (28-35) extension of these peptides favored VIP receptor recognition. Their N-terminal extremity was not necessary for binding and for ensuing adenylate cyclase activation, illustrating again the atypical coupling of VIP receptors with the effector enzymatic system, in rat liver membranes.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology; D010455:Peptides / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D018005:Receptors, Vasoactive Intestinal Peptide
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D010455:Peptides; D011956:Receptors, Cell Surface; D018005:Receptors, Vasoactive Intestinal Peptide; C040442:heliodermin; D000262:Adenylyl Cyclases