CLONING AND PHARMACOLOGICAL CHARACTERIZATION OF BRADYKININ RECEPTORS

A human B-2 bradykinin receptor cDNA was cloned from the lung fibrobla st cell line, CCD-Lu. This clone was utilized to isolate a genomic clo ne of a mouse B-2 bradykinin receptor. Both clones encode a protein th at has the predicted characteristics of a seven transmembrane domain G -protein-coupled receptor. The DNA sequence of these two clones is 84% identical in the putative coding region. The clones have been heterol ogously expressed in a mammalian cell line lacking endogenous bradykin in receptors, COS-7, and a comparative analysis of their pharmacology was done. Both clones exhibit properties characteristic of the B-2 bra dykinin receptor, binding bradykinin with high affinity (K-D = 0.1-0.2 nM) and binding des-Arg(9) bradykinin with a very low affinity (IC50 > 5 mu M). Interestingly, the mouse B-2 bradykinin receptor has a 60-8 0 fold higher affinity than the human B-2 bradykinin receptor for the peptide antagonists D-Arg(0)[Hyp(3),Thi(5,8),D-Phe(7)]bradykinin and D -Arg(0)[Hyp(3),D-Phe(7)]bradykinin.