Photoaffinity labeling of mammalian alpha 1-adrenergic receptors. Identification of the ligand binding subunit with a high affinity radioiodinated probe.

Journal Article

We have synthesized and characterized a novel high affinity radioiodinated alpha 1-adrenergic receptor photoaffinity probe, 4-amino-6,7-dimethoxy-2-[4-[5-(4-azido - 3 - [125I]iodophenyl) pentanoyl] - 1 - piperazinyl] quinazoline. In the absence of light, this ligand binds with high affinity (KD = 130 pM) in a reversible and saturable manner to sites in rat hepatic plasma membranes. The binding is stereoselective and competitively inhibited by adrenergic agonists and antagonists with an alpha 1-adrenergic specificity. Upon photolysis, this ligand incorporates irreversibly into plasma membranes prepared from several mammalian tissues including rat liver, rat, guinea pig, and rabbit spleen, rabbit lung, and rabbit aorta vascular smooth muscle cells, also with typical alpha 1-adrenergic specificity. Autoradiograms of such membrane samples subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveal a major specifically labeled polypeptide at Mr = 78,000-85,000, depending on the tissue used, in addition to some lower molecular weight peptides. Protease inhibitors, in particular EDTA, a metalloprotease inhibitor, dramatically increases the predominance of the Mr = 78,000-85,000 polypeptide while attenuating the labeling of the lower molecular weight bands. This new high affinity radioiodinated photoaffinity probe should be of great value for the molecular characterization of the alpha 1-adrenergic receptor.

Full Text

Duke Authors

Cited Authors

  • Leeb-Lundberg, LM; Dickinson, KE; Heald, SL; Wikberg, JE; Hagen, PO; DeBernardis, JF; Winn, M; Arendsen, DL; Lefkowitz, RJ; Caron, MG

Published Date

  • February 25, 1984

Published In

Volume / Issue

  • 259 / 4

Start / End Page

  • 2579 - 2587

PubMed ID

  • 6321475

International Standard Serial Number (ISSN)

  • 0021-9258

Language

  • eng

Conference Location

  • United States