We have identified a conserved family of genes related to Drosophila eag, which encodes a distinct type of voltage-activated K+ channel. Three related genes were recovered in screens of cDNA libraries from Drosophila, mouse, and human tissues. One gene is the mouse counterpart of eag; the other two represent additional subfamilies. The human gene maps to chromosome 7. Family members share at least 47% amino acid identity in their hydrophobic cores and all contain a segment homologous to a cyclic nucleotide-binding domain. Sequence comparisons indicate that members of this family are most closely related to vertebrate cyclic nucleotide-gated cation channels and plant inward-rectifying K+ channels. The existence of another family of K+ channel structural genes further extends the known diversity of K+ channels and has important implications for the structure, function, and evolution of the superfamily of voltage-sensitive ion channels.
Warmke et al. (1994) studied this question.