A monoclonal antibody to a conserved sequence in the extracellular domain recognizes the angiotensin II AT1 receptor in mammalian target tissues.

We have generated hybridomas which secrete monoclonal antibodies to the AT1 subtype of the angiotensin II receptor (AT1 receptor). These were obtained after immunization of Balb C/c mice with synthetic peptides representing sequences from either the extracellular domain (residues 8-17) or the intracellular domain (residues 229-237) of the AT1 receptor. Hybridoma populations were first screened for the production of antibodies which bound to rat liver cells. Further selection, and cloning by limiting dilution, was carried out for antibodies which bound specifically to rat adrenal glomerulosa cells. Confirmation that the antibody designated 6313/G2 interacted with the angiotensin II receptor was obtained using COS-7 cells transfected with AT1A receptor cDNA. In particular, the initial characterization of 6313/G2 showed specific immunofluorescence of vascular endothelium.