Alignment of the predicted <i>Lym</i>P2X amino acid sequence with mammalian and lower organism P2X receptors.

<p>The <i>Lym</i>P2X amino acid sequence (LymP2X) was aligned with human P2X1-6 (P51575, Q9UBL9, P56373, Q99571, Q93086, O15547), rat P2X2 (P49653), rat P2X4 (P51577), <i>Schistosoma mansoni</i> P2X (smP2X) (Q65A65) and <i>Hypsibius dujardini</i> P2X (HdP2X) (ACL14328) using CLUSTALW software. Equivalent residues in the two transmembrane domains (TM1 and TM2) of the zP2X4 crystal structure <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Kawate1" target="_blank">[9]</a> are indicated as horizontal blue bars. Highlighted conserved residues are numbered according to the hP2X1 sequence. Residues involved in ATP binding <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Hattori1" target="_blank">[5]</a> are highlighted in red. Ten conserved cysteine residues which form five disulphide bonds <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Ennion1" target="_blank">[3]</a> are in grey with yellow text and the consensus protein kinase C phosphorylation site (T18) in blue. Black arrows with light blue shaded amino acid sequence indicate the locations of CODHOP PCR primer pairs 1 and 2 used to identify <i>Lym</i>P2X (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone-0050487-t001" target="_blank">Table 1</a>). Rat P2X4 residues thought to be involved in the interaction with ivermectin (Q36, L40, V43, V47 W50, N338, G342, L346, A349 and I356) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Jelinkova1" target="_blank">[59]</a> are highlighted in purple with yellow text. Residues shown to be involved in the actions of metal ions are shaded orange where human P2X2 H204, H209 and H330 control access of zinc to its binding site <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Punthambaker1" target="_blank">[55]</a>, H120 and H213 in rat P2X2 are involved in the formation of an intersubunit zinc binding site <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Clyne1" target="_blank">[52]</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Nagaya1" target="_blank">[54]</a> and D138, H140 and C132 in rat P2X4 are involved in the inhibitory modulation by metal ions <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Coddou2" target="_blank">[56]</a>. A cluster of four positively charged residues thought to be involved in the actions of suramin and NF449 at hP2X1 (K136, K138, R139 and K140) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-ElAjouz1" target="_blank">[60]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Sim2" target="_blank">[61]</a> are shaded light green with yellow text whilst a lysine residue thought to be involved in PPADS action at P2X1 and P2X2 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487#pone.0050487-Buell1" target="_blank">[62]</a> is shaded dark green with white text (K249).