Mammalian PI - and & Adrenergic Receptors IMMUNOLOGICAL AND STRUCTURAL COMPARISONS

6,and b2-adrenergic receptors, pharmacologically distinct proteins, have been reported to be structurally dissimilar. In the present study three techniques were employed to compare the nature of mammalian &and Bz-adrenergic receptors. Antibodies against each of the receptor subtypes were raised separately. Polyclonal antisera against &-receptors f rat fat cells were raised in mice, and antisera against &-receptors of guinea pig lung were raised in rabbits. Receptors purified from rat fat cells (b1-), 549 mouse lymphoma cells (/Iz-), and rat liver (f12-) were probed with these antisera. Each anti-receptor antisera demonstrated the ability to immunopr~ipitate purified receptors of both &and &subtypes. The mobility of &receptors subjected to polyacrylamide gel electrophoresis was probed using antireceptor antibodies and nitrocellulose blots of the gels. Fat cell &-adrenergic receptors display M, = 67,000 under reducing conditions and M, = 54,000 under nonreducing conditions, as previously reported (Moxham, C. P., and Malbon, C. C. (1985) Biochemietry 24, 6072-6077). Both &and &-receptors displayed this same shift in electrophoretic mobility observed in the presence as compared to the absence of disulfide bridge-reducing agents, as detected both by autoradiography of the radiolabeled receptors and by immunoblotting of native receptors. Finally, isoelectric focusing of purified radioiodinated B1and B2-adrenergic receptors revealed identical isoelectric points. These data are the first to provide analyses of immunological, structural, and biochemical features of &and &-subtypes in tandem and underscore the structural similarities that exist between these pharmacologically distinct receptors.