J. Biol. Chem., Vol. 261, Issue 17, 7710-7716, 06, 1986
Mammalian alpha 1-adrenergic receptor. Purification and characterization of the native receptor ligand binding subunit
JW Lomasney, LM Leeb-Lundberg, S Cotecchia, JW Regan, JF DeBernardis, MG Caron and RJ Lefkowitz
alpha 1-Adrenergic receptors from a cultured smooth muscle cell line (DDT1
MF-2) have been solubilized with digitonin and purified to apparent
homogeneity by sequential chromatography on a biospecific affinity support
(Sepharose-A55453 (4-amino-6,7-dimethoxy-2-[4-[5-(4- amino-3-phenyl)
pentanoyl]-1-piperazinyl]-quinazoline), an alpha 1 receptor-selective
antagonist), a wheat germ agglutinin-agarose gel, and a high performance
steric exclusion liquid chromatography column. Sodium dodecyl
sulfate-polyacrylamide gel electrophoresis and autoradiography of iodinated
purified receptor preparations reveals a peptide with an apparent Mr =
80,000 that co-migrates with the peptide labeled by the specific alpha
1-adrenergic receptor photoaffinity probe
4-amino-6,7-dimethoxy-2-[4-[5-(4-azido-3-[125I]iodophenyl)pentanoyl] -1-
piperazinyl] quinazoline. The specific activity (approximately 13,600 pmol
of ligand binding/mg of protein) of purified receptor preparations is
consistent with that expected for a pure peptide of Mr = 80,000 containing
a single ligand binding site. Overall yields approximate 14% of initial
crude particulate binding. The purified receptor preparations bind agonist
and antagonist ligands with appropriate alpha 1-adrenergic specificity,
stereoselectivity, and affinity. Peptide maps of the pure alpha
1-adrenergic receptor and the pure human platelet alpha 2-adrenergic
receptor (Regan, J.W., Nakata, H., DeMarinis, R.M., Caron, M.G., and
Lefkowitz, R.J. (1986) J. Biol. Chem. 261, 3894-3900) using several
different proteases suggest that these two receptors show little if any
structural homology.