Sequence diversity of voltage-gated potassium channels in an electric fish

Cloning of voltage-gated K+ channels has indicated that these channels constitute a diverse family of genes that have been subclassified into four closely related gene families Kv1-Kv4 (Shaker, Shab, Shaw, Shal). A PCR approach has been used to assess the diversity of K+ channels in the weakly electric fish Apteronotus leptorhynchus, which is a well studied model of sensory processing. Degenerate primers specific for the highly conserved pore and S6 transmembrane domains of the K+ channel families were used to amplify an intronless 124 bp fragment from fish genomic DNA. DNA sequence analysis of a large number of these fragments has identified 19 putative K+ channels, each of which can be classified into one of the four major families. Ten fall into Kv1 class, two in the Kv2 class, five in the Kv3 class and two in the Kv4 class. The results indicate that the duplications that gave rise to multiple genes within each of the K+ channel families predate the divergence of the Actinopterygii and Sarcopterygii lineages (400 million years ago) during early vertebrate evolution.