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E. Kim, T.A. Day, J.L. Bennett and R.A. Pax
Parasitology 110:171-180
We have isolated a cDNA (Skvl.l) encoding a shaker-related K+ channel from an adult cDNA library of the human parasitic trematode Schistosoma mansoni. The deduced amino acid sequence (512aa, 56.5 kDa) contains 6 putative membrane-spanning domains (Sl-S6) and a pore-forming domain (H5). Skvl.l is grouped in the Shaker family, but forms a unique branch within this family, on the basis of dendrogram analysis. Skvl.l shows significant sequence identity with most other Shaker channels, with 64-74% identity in the core region (Sl-S6). It has the highest sequence identity with the K+ channel (Ak0la) from Aplysia. Northern blot analysis dedected a single primary transcript of 2.8kb. Souther blot analysis indicated that Skvl.l is present as a single copy in the genomic DNA of S. mansoni. Expression of Skvl.l in Xenopus oocytes produced a rapidly activating and inactivating outward K+ current whish is highly sensitive to 4-aminopyridine, but is insensitive to tetraethylammoniium, mast cell degranulating peptide, dendrotoxin and charybdotoxin. The presence of a Shaker homologue in Schistosoma suggests that Sh subfamilies may exist in other lower invertebrates as well as platyhelminths.