FIGURE 1.

Characteristics of the ion access point of P2XRs. (A) Multiple sequence alignment of seven rat P2XRs compared to zP2X4.1R. The sequence alignments contain the amino acid residues that are homologous to the V47–V61 and K326–N338 segments of rP2X4R (green shade), and the positively and negatively charged residues are indicated. (B) The surface landscape of the homology model for rP2X4R in a closed and open state; the entire molecule (left panels) and the selected regions (right panels). The residues comprising the peptide segments from V47–V61 and K326–N338 are presented in green; double arrows and numbers show average distances encompassing the ion entrance point. The Table within the insets summarizes the ion radii of physiologically permeable ions through P2X4R and cadmium ions in hydrated and non-hydrated states.