A locked-on, constitutively active mutant of the adenosine A1 receptor

We studied the wild-type human adenosine A1 receptor and three mutant receptors, in which the glycine at position 14 had been changed into an alanine, a leucine, or a threonine residue. All receptors were characterized in radioligand binding experiments, the wild-type and the Gly14Thr mutant recepto...

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Bibliographic Details
Published in:European journal of pharmacology 2005-03, Vol.510 (1-2), p.1-8
Main Authors: DE LIGT, Rianne A. F, RIVKEES, Scott A, LORENZEN, Anna, LEURS, Rob, IJZERMAN, Ad P
Format: Article
Language:English
Subjects:
Adenosine - analogs & derivatives
Adenosine - metabolism
Adenosine - pharmacology
Animals
Binding, Competitive - drug effects
Biological and medical sciences
Cell Line
Cell Membrane - drug effects
Cell Membrane - metabolism
Cercopithecus aethiops
Colforsin - pharmacology
COS Cells
Cyclic AMP - metabolism
Guanosine 5'-O-(3-Thiotriphosphate) - metabolism
Guanosine Triphosphate - pharmacology
Humans
Kinetics
Medical sciences
Mutation
Pharmacology. Drug treatments
Plasmids - genetics
Radioligand Assay
Receptor, Adenosine A1 - genetics
Receptor, Adenosine A1 - metabolism
Sodium - pharmacology
Sulfur Radioisotopes
Theophylline - analogs & derivatives
Theophylline - pharmacology
Thiophenes - pharmacology
Transfection
Tritium
Xanthines - metabolism
Xanthines - pharmacology
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Summary:We studied the wild-type human adenosine A1 receptor and three mutant receptors, in which the glycine at position 14 had been changed into an alanine, a leucine, or a threonine residue. All receptors were characterized in radioligand binding experiments, the wild-type and the Gly14Thr mutant receptor in greater detail. Both receptors were allosterically modulated by sodium ions and PD81,723 (2-amino-4,5-dimethyl-3-thienyl-[3(trifluoromethyl)-phenyl]methanone), although in a different way. All mutant receptors appeared to be spontaneously or "constitutively" active in a [35S]GTPgammaS binding assay, the first demonstration of the existence of such CAM (constitutively active mutant) receptors for the adenosine A1 receptor. The Gly14Thr mutant receptor was also constitutively active in another functional assay, i.e., the inhibition of forskolin-induced cAMP production in intact cells. Importantly, this mutant displayed a peculiar "locked-on" phenotype, i.e., neither agonist nor inverse agonist was capable of modulating the basal activity in both the GTPgammaS and the cAMP assay, unlike the wild-type and the two other mutant receptors.
ISSN:0014-2999
1879-0712
DOI:10.1016/j.ejphar.2005.01.007