Characterization of beta-adrenergic receptors in synaptic membranes from rat cerebral cortex and cerebellum
Beta-adrenergic receptor ligand binding sites have been characterized in synaptic membranes from rat cerebral cortex and cerebellum using radioligand binding techniques. The equilibrium and kinetic properties of binding were assessed. The binding sites were non-interacting and exhibited two states of agonist binding which were sensitive to guanyl nucleotide. Synaptic membranes from cerebral cortex contained an equal number of beta/sub 1/- and beta/sub 2/-receptors; membranes from cerebellum possessed more beta/sub 2/-than beta/sub 1/-receptors. Photoaffinity labeling experiments revealed two different beta-adrenergic receptor polypeptides, R/sub 1/ and R/sub 2/ (and possibly a third, R/sub 3/) in synaptic membranes. The ratios of incorporation of photoaffinity label into R/sub 1/:/sub 2/ were approximately 1:1 (cerebral cortex) and 5:1 (cerebellum). Photoaffinity labeling of R/sub 1/ and R/sub 2/ was inhibited equally well by both agonist and antagonist in synaptic membranes from cerebellum; whereas agonist was a less potent inhibitor in membranes from cerebral cortex. Both subtypes of beta-adrenergic receptors exhibited the same apparent molecular weight in synaptic membranes from cerebral cortex. The beta-adrenergic receptors in synaptic membranes from cerebral cortex and cerebellum were glycoproteins which exhibited the same apparent molecular weight after exposure to endoglycosidase F. The partial proteolytic digest maps of photoaffinity labeled beta-adrenergic receptors from rat cerebral cortex, cerebellum, lung and heart were compared.
- Research Organization:
- Wisconsin Univ., Madison (USA)
- OSTI ID:
- 6520858
- Country of Publication:
- United States
- Language:
- English
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ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
BRAIN
CARBOHYDRATES
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
CEREBELLUM
CEREBRUM
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ORGANS
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SYMPATHOMIMETICS
TRACER TECHNIQUES
VERTEBRATES