Purification of the beta-adrenergic receptor. Identification of the hormone binding subunit.

5, 8) but no information on the subunit structure has been described.In the studies presented here we have used both affinity and ion exchange chromatography to purify the /3adrenergic receptor.The specificity of the binding of P-adrenergic agents to the purified protein as well as several of its physicochemical properties suggest that a M, = 58,000 peptide contains the hormone binding site of the P-adrenergic receptor of frog erythrocytes.EXPERIMENTAL PROCEDURES Materials-Alprenolol hydrochloride was generously supplied by Hassle Pharmaceutical Co., Sweden.All other catecholamines and drugs were from sources previously described (3).Digitonin, obtained from Baker Chemical Co., was prepared by heating a 1.58 aqueous solution at 95-100 "C, and then the solution was allowed to stand 2- 4 days at 25 "C and filtered through Whatman No. 2 and Millipore HAWP filters in order to remove insoluble material.['"HIDihydroalprenolol (42-47 Ci/mmol) and carrier-free NaI2'1 were from New England Nuclear.Bisoxirane (1,4-butanediol diglycidylether), iodoacetamide and cyanogen bromide were from Sigma.Premixed SDS'polyacrylamide gel electrophoresis standards (phosphorylase b, M, I The abbreviations used are: SDS, sodium dodecyl sulfate; PAGE, polyacrylamide gel electrophoresis.