The hydrophobic tryptic core of the beta-adrenergic receptor retains Gs regulatory activity in response to agonists and thiols.

摘要: The function of structural domains the beta-adrenergic receptor were probed by studying ability tryptic fragments to catalyze binding guanosine-5'-O-(3-thiotriphosphate (GTP gamma S) GTP-binding regulatory protein, Gs. beta-Adrenergic purified from turkey erythrocytes was treated with trypsin under nondenaturing conditions. Such treatment decreased ligand activity only 15-25%. Active components limit digest repurified affinity chromatography on alprenolol-agarose and then reconstituted Gs into unilamellar phospholipid vesicles. After reconstitution, proteolyzed able agonist-stimulated GTP S at a rate extent equivalent that nonproteolyzed receptor. also partially activated upon reduction dithiothreitol, as previously reported for intact (Pedersen, S.E., Ross, E.M. (1985) J. Biol. Chem. 260, 14150-14157). repurified, active contained two detectable peptides. One, approximately 2 X 10(4) Da, either four or five amino-terminal membrane-spanning plus intervening hydrophilic loops but not extracellular, glycosylated peptide. second, 9,000-10,000 composed essentially carboxyl-terminal loop. These data indicate most large intracellular loop hydrophilic, region are necessary regulation