Molecular characterization of Shaker, a Drosophila gene that encodes a potassium channel

The Drosophila Shaker ('Sh) gene appears to encode a type of voltage-sensitive potassium (K +) channel called the A channel. We have isolated Sh as part of a 350 kb chromosomal walk. The region around Sh contains four identified transcription units. We find that Sh corresponds to a very large transcription unit encompassing a total of about 95 kb of genomic DNA and split by a major 85 kb intron. Sh has multiple hydrophobic domains that have a high probability of being membrane-spanning, consistent with the proposal that it encodes an ion channel.