Abstract
On the basis of electrophysiological analysis of Shaker mutants, the Shaker locus of Drosophila melanogaster has been proposed to encode a structural component of a voltage-dependent potassium channel, the A channel. Unlike sodium channels, acetylcholine receptors, and calcium channels, K+ channels have not been purified biochemically. To facilitate biochemical studies of a K+ channel, genomic DNA from the Shaker locus has been cloned. Rearrangements in five Shaker mutants have been mapped to a 60-kilobase segment of the genome. Four complementary DNA clones have been analyzed. These clones indicate that the Shaker gene contains multiple exons distributed over at least 65 kilobases of genomic DNA in the region where the mutations mapped. Furthermore, the gene may produce several classes of alternatively spliced transcripts. Two of the complementary DNA clones have been sequenced and their sequences support the hypothesis that Shaker encodes a component of a K+ channel.
