A FAMILY OF POTASSIUM CHANNEL GENES RELATED TO EAG IN DROSOPHILA AND MAMMALS

We have identified a conserved family of genes related to Drosophila e ag, which encodes a distinct type of voltage-activated K+ channel. Thr ee related genes were recovered in screens of cDNA libraries from Dros ophila, mouse, and human tissues. One gene is the mouse counterpart of eag; the other two represent additional subfamilies. The human gene m aps to chromosome 7. Family members share at least 47% amino acid iden tity in their hydrophobic cores and all contain a segment homologous t o a cyclic nucleotide-binding domain. Sequence comparisons indicate th at members of this family are most closely related to vertebrate cycli c nucleotide-gated cation channels and plant inward-rectifying K+ chan nels. The existence of another family of K+ channel structural genes f urther extends the known diversity of K+ channels and has important im plications for the structure, function, and evolution of the superfami ly of voltage-sensitive ion channels.