title: Allosteric modulators affect the internalization of human adenosine A1 receptors.
abstract: To study the effect of allosteric modulators on the internalization of human adenosine A(1) receptors, the receptor was equipped with a C-terminal yellow fluorescent protein tag. The introduction of this tag did not affect the radioligand binding properties of the receptor. CHO cells stably expressing this receptor were subjected during 16 h to varying concentrations of the agonist N(6)-cyclopentyladenosine (CPA) in the absence or presence of 10 microM of the allosteric enhancer PD 81,723 ((2-amino-4,5-dimethyl-3-thienyl)-[3-(trifluoromethyl)phenyl]methanone) or the allosteric inhibitor SCH-202676 (N-(2,3-diphenyl-1,2,4-thiadiazol-5(2H)-ylidene)methanamine). CPA itself was able to internalize 25% and 40% of the receptors at a concentration of 400 nM or 4 muM, respectively. Addition of either PD 81,723 or SCH-202676 alone had no effect on internalization. However, with PD 81,723 a slight amount of internalization was obtained already at 40 nM of CPA and at 400 nM CPA 59% of the receptors internalized. SCH-202676 on the other hand effectively prevented CPA-induced internalization of the receptor.
authors.affiliation: Department of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, The Netherlands.
authors.forename: Elisabeth C
authors.initials: EC
authors.lastname: Klaasse
authors.forename: Gijs
authors.initials: G
authors.lastname: van den Hout
authors.forename: Sophie F
authors.initials: SF
authors.lastname: Roerink
authors.forename: Willem J
authors.initials: WJ
authors.lastname: de Grip
authors.forename: Ad P
authors.initials: AP
authors.lastname: Ijzerman
authors.forename: Margot W
authors.initials: MW
authors.lastname: Beukers
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000494:Allosteric Regulation; D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D011869:Radioligand Assay; D043682:Receptor, Adenosine A1 / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013830:Thiadiazoles; D013844:Thiazoles / Q000494:pharmacology; D013876:Thiophenes / Q000494:pharmacology; D014162:Transfection; D014316:Tritium; D014970:Xanthines / Q000378:metabolism
chemical_list: D008164:Luminescent Proteins; D043682:Receptor, Adenosine A1; D011993:Recombinant Fusion Proteins; C418425:SCH-202676; D013830:Thiadiazoles; D013844:Thiazoles; D013876:Thiophenes; D014970:Xanthines; D014316:Tritium; C075004:PD 81723; C048599:N(6)-cyclopentyladenosine; C051360:1,3-dipropyl-8-cyclopentylxanthine; D000241:Adenosine