title: Specific labelling of high-affinity vasoactive intestinal peptide receptors in rat liver membranes by a growth hormone-releasing factor analog.
abstract: (125I-His1, D-Ala2, Nleu27)-growth hormone-releasing factor (GRF) (1-29)-NH2, initially developed as a possible radioligand for identifying GRF receptors in the anterior pituitary, was found to bind to rat hepatic membranes. The tracer was stable, bound rapidly and reversibly, and its dissociation was accelerated by GTP. Radioligand binding was enhanced by the divalent cations Mg2+, Ca2+ and Mn2+ and inhibited by the chelating agent EDTA. Vasoactive intestinal peptide (VIP), PHI, secretin, GRF(1-29)-NH2, (His1, D-Ala2, Nleu27)-GRF(1-29)-NH2, and (D-Ala2, Nleu27)-GRF(1-29)-NH2 dose-dependently inhibited tracer binding. The order of potency of the unlabelled peptides tested suggested that (125I-His1, D-Ala2, Nleu27)-GRF(1-29)-NH2 specifically identified a high-affinity subclass of VIP receptors in rat liver membranes.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002413:Cations, Divalent / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D013007:Growth Hormone-Releasing Hormone / Q000031:analogs & derivatives* / Q000378:metabolism; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D008024:Ligands; D008099:Liver / Q000378:metabolism*; D008566:Membranes / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D051381:Rats; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism*; D018005:Receptors, Vasoactive Intestinal Peptide
chemical_list: D002413:Cations, Divalent; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D010455:Peptides; D011964:Receptors, Gastrointestinal Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; C050822:somatotropin releasing hormone-(1-29), 1-His-2-Ala-27-Nle-; C040442:heliodermin; D013007:Growth Hormone-Releasing Hormone; D004492:Edetic Acid