Mammalian alpha 1-adrenergic receptor. Purification and characterization of the native receptor ligand binding subunit

• Published in: The Journal of biological chemistry Vol. 261; no. 17; pp. 7710 - 7716
• Main Authors: Lomasney, J W, Leeb-Lundberg, L M, Cotecchia, S, Regan, J W, DeBernardis, J F, Caron, M G, Lefkowitz, R J
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.06.1986; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Binding, Competitive; Cell Line; Cell Membrane - metabolism; Kinetics; Ligands; Macromolecular Substances; Molecular Weight; Muscle, Smooth; Peptide Fragments - analysis; Receptors, Adrenergic, alpha - isolation & purification; Receptors, Adrenergic, alpha - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)57458-0

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.