CLONING AND PHARMACOLOGICAL CHARACTERIZATION OF A RABBIT BRADYKININ B-1 RECEPTOR

A rabbit B-1 bradykinin receptor cDNA was isolated from a rabbit aorta smooth muscle cell library. The 1223 bp cDNA clone encodes a protein of 352 amino acids which is 78% identical to the human bradykinin B-1 receptor protein. Heterologous expression of the rabbit B-1 receptor c DNA in COS-7 cells imparts a high affinity specific binding for H-3-la beled[des-Arg(10)Leu(9)]kallidin. Scatchard analysis indicates that th e receptor binds the radiolabeled ligand with a K-d of 0.5 nM. The abi lity of kallidin (Lys-bradykinin) and bradykinin analogues to compete with binding of H-3-labeled [des-Arg(10),Leu(9)]kallidin was determine d and defined a rank order of potency: [des-Arg(10),Leu(9)]kallidin = [des-Arg(10)]kallidin > [des-Arg(9)]bradykinin = kallidin >> bradykini n. This receptor exhibits the classical B-1 pharmacological property o f preferentially binding to kinin analogues which lack the C-terminal arginine. In addition, the affinities for [des-Arg(10)]kallidin and [d es-Arg(10),Leu(9)]kallidin are 100-fold higher than those for the corr esponding bradykinin analogues [desArg(9)]bradykinin and [des-Arg(9),L eu(8)]bradykinin which lack the N-terminal lysine. This pharmacologica l profile is characteristic of the B-1 receptor subtype.