Characterization of bradykinin receptors solubilized from rat uterus and NG108-15 cells

In this paper we report the solubilization of bradykinin B2 binding sites from membranes prepared from NG 108-15 tumours and rat uterus with retention of binding activity. Digitonin was found to solubilize the receptors from both tissues, and the addition of CHAPS increased the yield of soluble receptor from rat uterus only. The affinity of a range of bradykinin analogues has been shown to have the same rank order for both the soluble and membrane receptors from both tissues, and in corresponding functional assays. In addition, the binding of bradykinin ligands to the soluble and membrane receptors is similarly modulated by the presence of sodium ions. We conclude that the soluble binding sites correspond to the physiological bradykinin B2 receptor present in these tissues.