RT Journal Article SR Electronic T1 Structural Analysis of Angiotensin IV Receptor (AT4) from Selected Bovine Tissues JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 1075 OP 1083 VO 289 IS 2 A1 Jian-Hua Zhang A1 Jodie M. Hanesworth A1 Michael F. Sardinia A1 Jeremiah A. Alt A1 John W. Wright A1 Joseph W. Harding YR 1999 UL http://jpet.aspetjournals.org/content/289/2/1075.abstract AB The angiotensin IV receptor (AT4) receptor is widely distributed in both species and tissues. This broad distribution appears to be reflected in an equally diverse repertoire of physiological actions that are mediated through AT4receptors. This breadth of location and function of AT4receptors encourages speculation that multiple AT4 isoforms might exist. In this study, we compared the structural properties of bovine AT4 receptors from adrenals, kidney, heart, thymus, bladder, aorta, and hippocampus. These comparisons were made using polyacrylamide gel electrophoresis or HPLC analysis of AT4receptors that had been covalently radiolabeled with the AT4-specific photoprobe 125I-benzoyl phenylalamine-angiotensin IV. Except for the hippocampal AT4 receptor, the binding subunit in all tissues had a molecular mass of approximately 165 kDa and associated with additional subunits via disulfide linkages. The hippocampal receptor was significantly smaller (150 kDa) and did not appear to possess other disulfide-linked subunits. The receptor was highly glycosylated in all tissues examined. Peptide mapping following cleavage of125I-labeled receptor with endopeptidase C or cyanogen bromide resulted in complex cleavage patterns. Together these mapping studies demonstrated the uniqueness of the hippocampal receptor and further suggested that other AT4 isoforms may exist and be variably distributed among bovine tissues. In agreement with the peptide mapping studies, differences in the binding pattern of several AngIV analogs were observed among the various tissues. The American Society for Pharmacology and Experimental Therapeutics