Molecular characterization of the beta-adrenergic receptor of frog erythrocytes

The beta-adrenergic receptor of the frog erythrocyte has been solubilized in an active form with digitonin and purified by affinity chromatography and high performance liquid chromatography. Purified preparations contain a single band of iodinated protein of apparent Mr = 58,000. This peptide appears to represent the ligand binding subunit of the receptor since purified preparations bind ligands with the same beta-adrenergic specificity as the solubilized or membrane-bound receptor, display the same isoelectric point and similar sedimentation characteristics in sucrose density gradients. The same ligand binding subunit can also be identified in partially purified receptor preparations or in membranes by photoaffinity labelling or photodependent crosslinking of two radiolabelled beta-adrenergic antagonists, p-azidobenzylcarazolol and p-aminobenzylcarazolol.