We have isolated an ATP receptor clone by screening a bovine corpus callosum cDNA library. The clone includ
es one open reading frame encoding for a protein of 373 amino acid r
esidu
es (42 kDa) which belongs to the G-protein-coupled receptor superfamily. In
Xenopusoocyt
es, this clone expr
essed an ATP receptor that triggered an oscillatory current in r
esponse to ATP (EC
50
es/glyphs/BQ4.GIF>20 μM). This current may have r
esulted from the activation of phospholipase C, the formation of inositol trisphosphate, and the release of Ca
2+, which then opens Cl
−channels. The order of potency for ATP receptor agonists was 2-MeSATP
es/glyphs/BQ4.GIF> ATP
es/glyphs/BML.GIF> α,β-MeATP > adenosine, and UTP was ineffective, a pharmacological profile consistent with that of a P
2ypurinoceptor. Northern blot analysis of mRNAs from various bovine brain tissu
es showed that the gene is expr
essed in the cerebellum, medulla, corpus callosum, hippocampus, superior colliculus, frontal cortex, and retina.
In situRT-PCR showed transcripts of the gene in many glial cells and endothelial cells of the corpus callosum. The cloned receptor may play an important role in neuron–glial signaling under normal and pathological conditions.
