Cloning and functional expression of a Shaker-related voltage-gated potassium channel gene from Schistosoma mansoni (Trematoda: Digenea).
We have isolated a cDNA (SKv1.1) encoding a Shaker-related K+ channel from an adult cDNA library of the human parasitic trematode Schistosoma mansoni. The deduced amino acid sequence (512 aa, 56.5 kDa) contains 6 putative membrane-spanning domains (S1-S6) and a pore-forming domain (H5). SKv1.1 is grouped in the Shaker family, but forms a unique branch within this family, on the basis of dendrogram analysis. SKv1.1 shows significant sequence identity with most other Shaker channels, with 64-74% identity in the core region (S1-S6). It has the highest sequence identity with the K+ channel (Ak01a) from Aplysia. Northern blot analysis detected a single primary transcript of 2.8 kb. Southern blot analysis indicated that SKv1.1 is present as a single copy in the genomic DNA of S. mansoni. Expression of SKv1.1 in Xenopus oocytes produced a rapidly activating and inactivating outward K+ current which is highly sensitive to 4-aminopyridine, but is insensitive to tetraethylammonium, 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.
Kim
E
E
Department of Pharmacology and Toxicology, Michigan State University, East Lansing 48824.
Day
T A
TA
Bennett
J L
JL
Pax
R A
RA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D015870:Gene Expression; D015723:Gene Library; D017238:Genes, Helminth / Q000235:genetics*; D015640:Ion Channel Gating; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D009865:Oocytes / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000096:biosynthesis / Q000145:classification / Q000235:genetics* / Q000502:physiology; D012313:RNA; D012550:Schistosoma mansoni / Q000235:genetics*; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D051637:Shaker Superfamily of Potassium Channels; D014981:Xenopus
D018076:DNA, Complementary; D015221:Potassium Channels; C039919:RNA, recombinant; D051637:Shaker Superfamily of Potassium Channels; D012313:RNA; D011188:Potassium