MOLECULAR-CLONING AND FUNCTIONAL-CHARACTERIZATION OF A MOUSE BRADYKININ B1 RECEPTOR GENE

The gene encoding a putative mouse bradykinin B1 receptor was cloned f rom a genomic library by low stringency screening. Analysis of two iso lated clones revealed a region which contains an open reading frame un interrupted by introns and encodes a 334 amino acid protein, which exh ibits seven potential transmembrane domains and is 68% identical to th e human and rabbit bradykinin B1 receptors, Lipopolysaccharide-treatme nt induces B1 receptor transcripts in the heart, liver and lung, Stabl e expression of the coding region in COS-7 cells resulted in high leve ls of binding sites for the specific B1 ligand des-Arg(10) kallidin (K -d = 1.3 nM; B-max = 51 fmol/mg protein). The rank order of affinity o f the receptor for the agonists and antagonists was: des Arg(9)BKdes-A rg(9)Leu(8)BKdrs-Arg(10)kallidin much greater than Hoe-140 = bradykini n. Functional coupling of the cloned receptor was demonstrated by the dose-dependent effect of des-Arg(9)BK on the extracellular acidificati on rate in stably transfected COS-7 cells. This effect was not produce d by bradykinin and could be blocked by the B1 antagonist des-Arg(9)Le u(8)BK. (C) 1996 Academic Press, Inc.