The Drosophila erg K+ channel polypeptide is encoded by the seizure locus

Theeagfamily of K+channels contains three known subtypes:eag,elk, anderg. Genes representing the first two subtypes have been identified in flies and mammals, whereas the third subtype has been defined only by the human HERG gene, which encodes an inwardly rectifying channel that is mutated in some cardiac arrhythmias. To establish the predicted existence of aDrosophilagene in theergsubfamily and to learn more about the structure and biological function of channels within this subfamily, we undertook a search for theDrosophilacounterpart of HERG. Here we report the isolation and characterization of theDrosophila erggene. We show that it corresponds with the previously identified seizure (sei) locus, mutations of which cause a temperature-sensitive paralytic phenotype associated with hyperactivity in the flight motor pathway. These results yield new insights into the structure and evolution of theeagfamily of channels, provide a molecular explanation for theseimutant phenotype, and demonstrate the important physiological roles oferg-type channels from invertebrates to mammals.