title: Specific photoaffinity labelling of inhibitory adenosine receptors.
abstract: N6(L-phenylisopropyl)adenosine (L-PIA) and N6(3-iodo-4-azido benzyl)-adenosine (IAzBA) inhibit the adenylate cyclase activity in synaptic membranes of chick cerebellum via Ri adenosine receptors. [3H]L-PIA and [125I]AzBA bind to these membranes with Kd values of approximately 1 nM and Bmax values of approximately 1000 fmol/mg protein. Photolysis of [125I]AzBA bound to synaptic membranes results in the specific incorporation of radioactivity into a protein with Mr = 36,000. This photoincorporation is blocked by simultaneous exposure to L-PIA, theophylline, an adenosine receptor antagonist, or Gpp(NH)p, but not by cytosine, suggesting that the 36,000 dalton protein is the Ri adenosine receptor or a subunit of the receptor that contains the adenosine binding site.
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives*; D000067956:Adenylyl Cyclase Inhibitors; D000345:Affinity Labels / Q000378:metabolism; D000818:Animals; D001386:Azides / Q000378:metabolism* / Q000494:pharmacology; D002531:Cerebellum / Q000378:metabolism*; D002645:Chickens; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D010660:Phenylisopropyladenosine / Q000378:metabolism* / Q000494:pharmacology; D010777:Photochemistry; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011983:Receptors, Purinergic; D013570:Synaptic Membranes / Q000378:metabolism*; D013806:Theophylline / Q000494:pharmacology
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D000345:Affinity Labels; D001386:Azides; D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D010660:Phenylisopropyladenosine; D006165:Guanylyl Imidodiphosphate; C046555:N(6)-(3-iodo-4-azidobenzyl)adenosine; D013806:Theophylline; D000241:Adenosine