title: Parathyroid hormone receptors of renal cortex: specific binding of biologically active, 125I-labeled hormone and relationship to adenylate cyclase activation.
abstract: Biologically active (125)I-labeled bovine parathyroid hormone (prepared by electrolytic iodination) and its synthetic NH(2)-terminal (1-34) biologically active fragment bound rapidly and specifically to a purified plasma membrane preparation from bovine renal cortex. Binding of labeled intact hormone or labeled NH(2)-terminal (1-34) peptide was inhibited competitively by unlabeled (1-34) peptide in the same range of concentrations that activated renal cortical 3':5'-adenylate cyclase (EC 4.6.1.1) in these membranes. The concentrations of synthetic (1-34) peptide for half-maximal inhibition of binding of labeled hormone as well as half-maximal activation of the enzyme were about 0.6 muM (2.5 mug/ml). Therefore it is likely that the binding activity studied represents a physiologically important renal receptor for parathyroid hormone. Biologically inactive (oxidized) forms of parathyroid hormone and (1-34) NH(2)-terminal peptide as well as calcitonin, glucagon, insulin, and epinephrine failed to competitively inhibit the binding of labeled (1-34) parathyroid hormone or activate adenylate cyclase in the renal cortical membrane preparation. Observations with the NH(2)-terminal (1-34) biologically active fragment of parathyroid hormone suggest that the COOH-terminal region of the molecule is not required for receptor binding.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D002116:Calcitonin / Q000494:pharmacology; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D004837:Epinephrine / Q000494:pharmacology; D005934:Glucagon / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D007457:Iodine Radioisotopes; D007672:Kidney Cortex / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D007700:Kinetics; D010281:Parathyroid Hormone / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000187:drug effects*
chemical_list: D007328:Insulin; D007457:Iodine Radioisotopes; D010281:Parathyroid Hormone; D011956:Receptors, Cell Surface; D002116:Calcitonin; D005934:Glucagon; D000262:Adenylyl Cyclases; D004837:Epinephrine