Identity of K⁺ channel homologues in pathogenic protozoa.

<p>Protein accession numbers are shown and NF denotes that no homologues were found. Number of predicted TMDs is indicated in parentheses. K⁺ channel homologues are classified on the basis of closest similarity to a particular subtype of human K⁺ channel subunit and according to the presence of characteristic functional domains, such as a charged TMD4 (K_v), the presence of a cyclic nucleotide-binding domain CNBD (K_CNG), or the presence of RCK domains (K_Ca). Where a protein showed similarity to more than one class of K⁺ channel, its accession number is shown in both relevant columns (<i>eg.</i> all K_v homologues are also K_Ca homologues).</p>*<p>K_CNG homologues which contain a CNBD, but also a charged TMD4;</p>a<p>likely non-selective or non-functional due to GY<u>R</u>D, GY<u>S</u>D or GY<u>S</u>E selectivity filter motifs;</p>b<p>no putative RCK domains or calmodulin-binding domains (CaMBDs) were detected in these proteins by searching the Conserved Domains Database, but in BLASTP searches of the human genome these proteins showed greatest sequence similarity to the K_Ca channel subtypes indicated in parentheses. The <i>P. falciparum</i> proteins XP_001609692 and XP_001350669 are identical to the previously described PfKch2 and PfKch1 proteins respectively <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032264#pone.0032264-Ellekvist1" target="_blank">[14]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032264#pone.0032264-Ellekvist2" target="_blank">[16]</a>. The <i>B. bovis</i> (XP_001610013) and <i>C. hominis</i> (XP_668687) proteins have been identified previously as orthologues of PfKch1 in <i>P. berghei</i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032264#pone.0032264-Ellekvist2" target="_blank">[16]</a>. In addition to the K⁺ channel homologues shown, homologues of putative adenylyl cyclase/K⁺ channel fusion proteins <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032264#pone.0032264-Muhia1" target="_blank">[123]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032264#pone.0032264-Weber1" target="_blank">[124]</a> that contain GXG motifs after their TMD6 domains were also identified in <i>P. falciparum</i> (XP_001348216), <i>P. knowlesi</i> (XP_002260946), <i>P. vivax</i> (XP_001616904), <i>T. gondii</i> (XP_002368352, XP_002370938 and XP_002367966), <i>C. muris</i> (XP_002140763), <i>C. hominis</i> (XP_666311) and <i>C. parvum</i> (XP_626352). Homologues of these proteins were absent in all other parasites examined.