Fig. 2.

Sequence alignment of regions surrounding the second transmembrane segments of select P2X receptor sequences. The horizontal black bar indicates the position of TMS2. Functionally important regions and residues, a Lys residue (K308 equivalent in rat P2X2 receptor), an Asp residue (conserved in the TMS2 of most P2X receptors), and the conserved YxxxK motif, are indicated by a filled circle, an asterisk symbol, and a gray bar, respectively. For species abbreviations, see Fig. 1 caption