Mutants of a temperature-sensitive two-P domain potassium channel.
Within the Caenorhabditis elegans genome there exist at least 42 genes encoding TWK (two-P domain K(+)) channels, potassium channel subunits that contain two pore regions and four transmembrane domains. We now report the first functional characterization of a TWK channel from C. elegans. Although potassium channels have been reported to be activated by a variety of factors, TWK-18 currents increase dramatically with increases in temperature. Two mutant alleles of the twk-18 gene confer uncoordinated movement and paralysis in C. elegans. Expression of wild-type and mutant TWK-18 channels in Xenopus oocytes showed that mutant channels express much larger potassium currents than wild-type channels. Promoter-green fluorescent protein fusion experiments indicate that TWK-18 is expressed in body wall muscle. Our genetic and physiological data suggest that the movement defects observed in mutant twk-18 animals may be explained by an increased activity of the mutant TWK-18 channels.
Kunkel
M T
MT
Departments of Anatomy, Washington University School of Medicine, Seattle, Washington, USA.
Johnstone
D B
DB
Thomas
J H
JH
Salkoff
L
L
D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins; D002478:Cells, Cultured; D002874:Chromosome Mapping; D015870:Gene Expression; D049452:Green Fluorescent Proteins; D008124:Locomotion / Q000235:genetics; D008164:Luminescent Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism; D016296:Mutagenesis; D009154:Mutation; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D009928:Organ Specificity; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014960:X Chromosome / Q000235:genetics; D014981:Xenopus
D029742:Caenorhabditis elegans Proteins; D008164:Luminescent Proteins; D015221:Potassium Channels; D011993:Recombinant Fusion Proteins; C427284:TWK-18 protein, C elegans; D049452:Green Fluorescent Proteins; D011188:Potassium