Novel subtype of human angiotensin II type 1 receptor: cDNA cloning and expression

Angiotensin II (AII) plays a major role in regulation of cardiovascular function and fluid homeostasis through the action of an AII type 1 receptor (AT1R). The cDNA encoding a novel subtype of human AT1R (AT1bR) was cloned from a human placental cDNA library. The full-length cDNA clone (1563 bp) encoded a polypeptide that consists of 359 amino acid (aa) residues with 97.2% aa identity to the human AT1aR. All the aa replacements between two human AT1Rs reside within the C-terminal half region of AT1R molecule. The 2.4-knt AT1bR mRNA is expressed in the lung, placenta and liver, and differs from AT1aR mRNA in its tissue distribution. The AT1bR expressed in COS-7 cells is pharmacologically distinct from the human AT1aR.