Deglycosylated mammalian beta 2-adrenergic receptors are still able to undergo functional coupling to Ns

Mammalian beta 2-adrenergic receptors (R) have been shown to be structurally heterogeneous with respect to glycosylation (Stiles et al. J. biol. Chem. 259, 8655 (1984). They are also heterogeneous with respect to functional coupling to Ns. The ternary H.R.Ns complex can be frozen in the presence of the alkylating reagent N-ethylmaleimide. In hamster lung membranes 45% of the receptors are agonist/N-ethylmaleimide sensitive (i.e. coupling-prone receptors). beta-Receptors in both native and isoproterenol/N-ethylmaleimide pretreated membrane preparations are retained by affinity chromatography on concanavalin A and wheat germ agglutinin and are equally sensitive to neuraminidase treatment. This is exhibited by the increase in mobility of the 125I-iodocyanopindolol-azide photoaffinity labeled receptor peptide in SDS-polyacrylamide gel electrophoresis. These observations suggest that there is no link between the structural and functional heterogeneity of the receptors. Moreover, both partial (using neuraminidase) and near total (using endoglycosidase F) deglycosylation of membrane-bound receptors does not affect the H.R.-Ns coupling capacity as compared to native receptors.