A POTASSIUM CHANNEL BETA-SUBUNIT RELATED TO THE ALDO-KETO REDUCTASE SUPERFAMILY IS ENCODED BY THE DROSOPHILA HYPERKINETIC LOCUS

Genetic and physiological studies of the Drosophila Hyperkinetic (Hk) mutant revealed defects in the function or regulation of K+ channels encoded by the Shaker (Sh) locus, The Hk polypeptide, determined from analysis of cDNA clones, is a homologue of mammalian K+ channel beta subunits (K-v beta). Coexpression of Hk with Sh in Xenopus oocytes increases current amplitudes and changes the voltage dependence and kinetics of activation and inactivation, consistent with predicted functions of Hk in vivo. Sequence alignments show that Hk, together with mammalian K-v beta, represents an additional branch of the aldo-keto reductase superfamily. These results are relevant to understanding the function and evolutionary origin of K-v beta.