Multiple alignment of the primary structure of potassium channel pores from 21 different species computed using Clustalw (http://www.ebi.ac.uk/clustalw/, European Bioinformatics Institute). The signature sequence TVGYGD on the selectivity was used as reference for the alignments. The segments S5, External loop, and P-helix were assigned using prediction of transmembrane helices and topology of protein software (HMMTOP, Hungarian Academy of Sciences, http://www.enzim.hu/hmmtop/). Residues from the beginning of segment S5 to the end of S6 were included in the alignment. RCK2 (Kv1.6), Rattus norvegicus (GI:116435); Kv1.5, Mus musculus (GI:2493594); SkCa-2, Homo sapiens (GI:37955868); KCNA10, Homo sapiens (GI:5031819); Kv1.2, Oryctolagus cuniculus (GI:9652317); Kv2.2, Homo sapiens (GI:27436974); KvEBN1, Homo sapiens (GI:2801452); Shaker, Drosophila melanogaster (GI:288442); SqKv1A, Schistosoma mansoni (GI:510098); Kv1.7, Homo sapiens (GI:14485555); Slack, Rattus norvegicus (GI:11177892); KcsA, Streptomyces lividans (1K4C); KvAP, Aeropyrum pernix (1ORQ); MthK, Methanothermobacter thermautotrophic (1LNQ); cSlo2, Caenorhabditis elegans (GI:71986737); RbSlo, Oryctolagus cuniculus (GI:46396500); mSlo3, Mus musculus (GI:86990444); mslo, Mus musculus (GI:347144); dSlo, Drosophila melanogaster (GI:62472831); rSlo, Rattus norvegicus (GI:58339363); mSlo1, Mus musculus (GI:111607492); hslo, Homo sapiens (GI:46396283).