CLONING AND EXPRESSION OF A COMPLEMENTARY-DNA ENCODING A BOVINE ADRENAL ANGIOTENSIN-II TYPE-1 RECEPTOR

ANGIOTENSIN II elicits different responses which affect cardiovascular, neuronal and electrolyte transport regulation 1. To understand the mechanisms responsible for its various actions, the receptor for angiotensin II has long been sought, but numerous attempts to purify the receptor have been unsuccessful owing to its instability and low concentration 2-6. We report here the expression cloning of a complementary DNA encoding a bovine angiotensin II receptor to overcome these difficulties. The receptor cDNA encodes a protein of 359 amino-acid residues with a transmembrane topology similar to that of other G protein-coupled receptors. COS-7 cells transfected with cDNA expressed specific and high-affinity binding sites for angiotensin II, angiotensin II antagonist and a non-peptide specific antagonist for type-1 receptor. Dithiothreitol inhibited ligand binding. The concentration of intracellular Ca2+ and of inositol-1,4,5-trisphospate increased in the transfected COS-7 cells in response to angiotensin II or angiotensin III, indicating that this receptor is the type-1 receptor for angiotensin II. Northern blot analysis revealed that the messenger RNA for this receptor is expressed in bovine adrenal medulla, cortex and kidney.