Determination of the molecular size of frog and turkey erythrocyte .beta.-adrenergic receptors by radiation inactivation

The beta sub(1)- and beta sub(2)-adrenergic receptors from turkey and frog erythrocyte plasma membranes, respectively, have been solubilized with digitonin and purified by sequential affinity and gel-permeation high-performance liquid chromatography. Examination of these preparations reveals the beta -adrenergic receptor to be composed entirely of M sub(r) 58,000 subunits. In contrast, for the beta sub(1)-adrenergic receptor of turkey erythrocytes, two distinct receptor peptides of M sub(r) 40,000 and 45,000 were identified. The data indicate that the peptides identified as the receptor subunit by purification and photoaffinity labeling contain a single ligand binding site for both the frog erythrocyte beta sub(2)-adrenergic receptor and the turkey erythrocyte beta sub(1)-adrenergic receptor.