Subtype-specific stimulation of [35S]GTPgammaS binding by recombinant alpha2-adrenoceptors.
We measured agonist-stimulated binding of the stable GTP-analog guanosine-5'-O-(3-[35S]thiotriphosphate) ([35S]GTPgammaS) as a functional assay to monitor G-protein activation by recombinant human alpha2-adrenoceptor subtypes alpha2A, alpha2B and alpha2C. (-)-Noradrenaline was a full agonist in all receptors. Dexmedetomidine, UK14,304, clonidine and oxymetazoline showed subtype-selectivity in efficacy. Dexmedetomidine was a full agonist at alpha2B and a partial agonist at alpha2A; UK14,304 was a full agonist at alpha2A and a partial agonist at alpha2B. Clonidine and oxymetazoline were weak partial agonists at the alpha2B-subtype, but appeared inactive at alpha2A and alpha2C. The [35S]GTPgammaS binding assay provides functional information on pertussis toxin-sensitive G-protein activation, complementing radioligand binding assays and conventional second messenger assays.
Department of Pharmacology and Clinical Pharmacology, University of Turku, Finland.
J M
JM
Peltonen
M
M
Pihlavisto
M
M
Scheinin
D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D006801:Humans; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism / Q000502:physiology; D013462:Sulfur Radioisotopes
C547768:ADRA2A protein, human; C547771:ADRA2B protein, human; C547774:ADRA2C protein, human; D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D018341:Receptors, Adrenergic, alpha-2; D013462:Sulfur Radioisotopes; D016244:Guanosine 5'-O-(3-Thiotriphosphate)