Photoaffinity cross-linking of a radioiodinated probe, /sup 125/I-A55453, into alpha 1-adrenergic receptors
We have synthesized and characterized a high-affinity alpha 1-adrenergic receptor probe, 4-amino-6,7-dimethoxy-2(4'- (5''(3'''-/sup 125/I-iodo-4'''-aminophenyl)pentanoyl)-1'-piperazinyl) quinazoline (/sup 125/I-A55453). This ligand binds reversibly to rat hepatic plasma membranes with high affinity (KD . 77 +/- 6 pM), and it labels the same number of specific prazosin-competable sites as the alpha 1-adrenergic receptor-selective radioligand (/sup 125/I) iodo-2-(beta-(4-hydroxyphenyl)-ethylaminomethyl)tetralone. Specific binding is stereoselective and competed for by alpha-adrenergic agents with an alpha 1-adrenergic receptor specificity. /sup 125/I-A55453 can be covalently photoincorporated into peptides of rat hepatic and splenic membranes using the bifunctional photoactive cross-linker, N-succinimidyl-6- (4'-azido-2'-nitrophenylamino)hexanoate. Following photolysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of labeled hepatic membranes reveals a major specifically labeled peptide of Mr . 82,000 (+/- 1,000) with minor peptides at Mr . 50,000 (+/- 500), and 40,000 (+/- 300). Covalent incorporation of /sup 125/I-A55453 into the Mr . 82,000 peptide is inhibited by adrenergic drugs with an alpha 1-adrenergic receptor specificity. Labeled splenic membranes demonstrate a broad band of photoincorporated radioactivity centered at Mr . 82,000, and covalent incorporation into this peptide is also attenuated with an alpha 1-adrenergic receptor specificity. This new high-affinity radioiodinated probe has features which should make it useful for the molecular characterization of alpha 1-adrenergic receptors in tissues.
- Research Organization:
- Duke Univ. Medical Center, Durham, NC
- OSTI ID:
- 6137524
- Journal Information:
- Mol. Pharmacol.; (United States), Vol. 26:2
- Country of Publication:
- United States
- Language:
- English
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SYMPATHOMIMETICS
RECEPTORS
AFFINITY
ANTIHYPERTENSIVE AGENTS
ATTENUATION
CELL MEMBRANES
CROSS-LINKING
IODINE 125
LABELLED COMPOUNDS
LIGANDS
LIVER
PEPTIDES
PHOTOSENSITIVITY
PYRIMIDINES
RATS
TRACER TECHNIQUES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZINES
BETA DECAY RADIOISOTOPES
BODY
CARDIOVASCULAR AGENTS
CELL CONSTITUENTS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
GLANDS
HETEROCYCLIC COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
POLYMERIZATION
PROTEINS
RADIOISOTOPES
RODENTS
SENSITIVITY
VERTEBRATES
550201* - Biochemistry- Tracer Techniques