Authors: Vardan T Karamyan Jason Arsenault Emanuel Escher Robert C Speth
Publish Date: 2010/04/13
Volume: 37, Issue: 3, Pages: 442-448
Abstract
A novel binding site for angiotensins II and III was recently discovered in brain membranes in the presence of the sulfhydryl reactive angiotensinase inhibitor parachloromercuribenzoate This binding site is distinctly different from the other known receptors for angiotensins AT1 AT2 AT4 and mas oncogene protein Ang 17 receptor Preliminary biochemical characterization studies have been done on this protein by crosslinking it with 125Ilabeled photoaffinity probes and solubilizing the radiolabeled binding site Polyacrylamide gel electrophoresis studies and isoelectric focusing indicate that this membrane bound binding site is a protein with a molecular weight of 70–85 kDa and an isoelectric point of ~7 Cyanogen bromide hydrolysis of the protein yielded two radiolabeled fragments of 125 and 25 kDa The protein does not appear to be Nglycosylated based upon the failure of PNGaseF to alter its migration rate on a 75 polyacrylamide gel The binding of angiotensin II to this protein is not affected by GTPγS or GppNHp suggesting that it is not a G proteincoupled receptor Further characterization studies are directed to identify this protein either as a novel angiotensin receptor an angiotensin scavenger clearance receptor or an angiotensinasePortions of this work were carried out at the University of Mississippi and were supported by the Peptide Radioiodination Service Center of the University of Mississippi This work is also supported by NHLBI HL096357 The authors thank Dr Kevin Catt for providing the Sar14N3Phe8Ang II used in this study
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