Multiple Products of the Drosophila Shaker Gene May Contribute to Potassium Channel Diversity

K+ channels are known through electrophysiology and pharmacology to be an exceptionally diverse group of channels. Molecular studies of the Shaker (Sh) locus in Drosophila have provided the first glimpse of K+ channel structure. The sequences of several Sh cDNA clones have been reported; none are identical. We have isolated and examined 18 additional Sh cDNAs in an attempt to understand the origin, extent, and significance of the variability. The diversity is extensive: we have already identified cDNAs representing at least nine distinct types, and Sh could potentially encode 24 or more products. This diversity, however, fits a simple pattern in which variable 3′ and 5′ ends are spliced onto a central constant region to yield different cDNA types. These different Sh cDNAs encode proteins with distinct structural features.