Photoaffinity labeling of mammalian alpha 1-adrenergic receptors. Identification of the ligand binding subunit with a high affinity radioiodinated probe.
1984; Elsevier BV; Volume: 259; Issue: 4 Linguagem: Inglês
10.1016/s0021-9258(17)43393-x
ISSN1083-351X
AutoresL.M. Fredrik Leeb-Lundberg, Kenneth E.J. Dickinson, Sarah L. Heald, Jarl E. S. Wikberg, P.‐O. Hagen, John F. DeBernardis, M J Winn, David L. Arendsen, Robert J. Lefkowitz, Marc G. Caron,
Tópico(s)Eicosanoids and Hypertension Pharmacology
ResumoWe have synthesized and characterized a novel high affinity radioiodinated al-adrenergic receptor photoaffinity probe, 4-amino-6,7-dimethoxy-2-[4-[5-(4azido -3 -[ 1251]iodophenyl)pentanoyl] -1piperazinyll quinazoline.In the absence of light, this ligand binds with high affinity (KO = 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 al-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 crl-adrenergic specificity.Autoradiograms of such membrane samples subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveal a major specifically labeled polypeptide at M , = 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 M , = 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 al-adrenergic receptor.Hormone receptors mediating the physiological responses to catecholamines can be divided into two main groups, a- and @-adrenergic, with two main subtypes of each (a, and a2 and / 3 , and p2) having been recognized.These different groups of receptors can be distinguished by their distinct affinities for various agonists and antagonists (1).The biochemical characterization of these receptors is presently in an early stage of development.At this time, more knowledge has been gained about the 8-adrenergic receptors than the a-adrenergic receptors.The p-adrenergic receptor has been isolated and purified from several tissues (2-5).In addition, the development of highly specific radioactive photoaffinity probes has
Referência(s)