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Updated: Jul 31, 2026

Proteomics to Identify Proteins Interacting with P2X2 Ligand-Gated Cation Channels
Published on: May 19, 2009
Conserved negatively charged residues are not required for ATP action at P2X(1) receptors
S J Ennion1, J Ritson, R J Evans
1Department of Cell Physiology and Pharmacology, University of Leicester, Leicester LE1 9HN, United Kingdom.
Abstract:
The role of conserved negatively charged aspartic (D) and glutamic (E) acid residues within the ectodomain of the human P2X(1) receptor were examined by alanine substitution mutagenesis. Effects on ATP potency and cell surface localisation were assessed in Xenopus oocytes using the two electrode voltage clamp technique and cell surface biotinylation. Of the eleven residues tested no major shifts in ATP potency were observed with EC(50) values for ATP ranging from 0.8 to 4.3 microM (compared to 1 microM ATP for wild-type P2X(1) receptors). Peak current amplitudes for mutants D86A and D264A where reduced by approximately 90% due to a corresponding reduction in both total protein and cell surface expression. These results demonstrate that individual conserved negatively charged amino acids are not essential for ATP recognition by the human P2X(1) receptor and coordinated binding of the positive charge on magnesium complexed ATP by negatively charged amino acids is not required.
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