Stable expression of human endothelin receptors ETA and ETB by transfected baby hamster kidney cells.

The cDNAs for human endothelin receptors ETA and ETB were subcloned into the eukaryotic expression vector pMPSV/CMV and transfected, in parallel with plasmids carrying resistances for hygromycin B and puromycin, into baby hamster kidney (BHK) cells. Cell clones constitutively expressing high levels of either receptor were obtained through the combined selective pressure of both antibiotics. This was further confirmed by Northern blot analysis using ETA- or ETB-specific oligonucleotide probes. The calculated KD for endothelin (ET)-1 binding to ETA and ETB were 2.2 x 10(-10) M and 5.3 x 10(-10) M, respectively. Competitive binding experiments using the different ET forms showed the expected isopeptide-selective and non-isopeptide-selective profiles for ETA and ETB, respectively. BQ 123, a specific ETA antagonist, competed with ET-1 for binding to ETA but not to ETB.