SK channels are a family of potassium channels with six transmembrane domains and are gated by intracellular Ca2+ ions independent of voltage. Four genes, SK1, SK2, SK3 and IK1, encode the family of SK channels in vertebrates. They are found throughout the nervous system, in smooth muscle, and in epithelial tissues of liver, pancreas, and kidney. Mammalian SK channels are sensitive to the honeybee venom apamin, and have small unitary conductance. We cloned the cDNA for the C. elegans</I> homologue of the SK3 channel, C03F11.1. RACE revealed that the gene surprisingly contains 7 exons upstream of the predicted start site, doubling the size of the predicted protein. The C-terminal half of the protein shows good homology to the mammalian gene, but the N-terminal half is novel. A promoter-gfp construct is expressed strongly in amphid neurons, ventral cord motorneurons, and tail ganglia. Western blots of the worm protein suggest that it is normally bound to calmodulin, as are mammalian SK channels. Patch-clamp analysis of C03F11.1 expressed in CHO cells shows a calcium current similar to that reported for mammalian SK3. We also found that apamin inhibits the conductance of these channels, similar to its effects on mammalian SK3.
tm1731</I> animals, created by the Mitani laboratory, are homozygous viable and appear to move normally. We are examining these animals more closely to determine if deletion of C03F11.1 causes subtle defects in motility or behaviour, and using RNAi to determine if deletion of more than one SK channel homologue has synergistic effects on behaviour.