J. Biol. Chem., Vol. 261, Issue 31, 14562-14570, Nov, 1986
Mammalian beta 1- and beta 2-adrenergic receptors. Immunological and structural comparisons
CP Moxham, ST George, MP Graziano, HJ Brandwein and CC Malbon
Beta 1- and beta 2-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
beta 1- and beta 2-adrenergic receptors. Antibodies against each of the
receptor subtypes were raised separately. Polyclonal antisera against beta
1-receptors of rat fat cells were raised in mice, and antisera against beta
2-receptors of guinea pig lung were raised in rabbits. Receptors purified
from rat fat cells (beta 1-), S49 mouse lymphoma cells (beta 2-), and rat
liver (beta 2-) were probed with these antisera. Each anti-receptor
antisera demonstrated the ability to immunoprecipitate purified receptors
of both beta 1- and beta 2- subtypes. The mobility of beta-receptors
subjected to polyacrylamide gel electrophoresis was probed using
antireceptor antibodies and nitrocellulose blots of the gels. Fat cell beta
1-adrenergic receptors display Mr = 67,000 under reducing conditions and Mr
= 54,000 under nonreducing conditions, as previously reported (Moxham, C.
P., and Malbon, C. C. (1985) Biochemistry 24, 6072-6077). Both beta 1- and
beta 2-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 beta 1- and beta 2-adrenergic receptors
revealed identical isoelectric points. These data are the first to provide
analyses of immunological, structural, and biochemical features of beta 1-
and beta 2-subtypes in tandem and underscore the structural similarities
that exist between these pharmacologically distinct receptors.