SEQUENCE DIVERSITY OF VOLTAGE-GATED POTASSIUM CHANNELS IN AN ELECTRICFISH

Cloning of voltage-gated K+ channels has indicated that these channels constitute a diverse family of genes that have been subclassified int o four closely related gene families Kv1-Kv4 (Shaker, Shab, Shaw, Shal l. A PCR approach has been used to assess the diversity of K+ channels in the weakly electric fish Apteronotus leptorhynchus, which is a wel l studied model of sensory processing. Degenerate primers specific for the highly conserved pore and S6 transmembrane domains of the K+ chan nel families were used to amplify an intronless 124 bp fragment from f ish genomic DNA. DNA sequence analysis of a large number of these frag ments has identified 19 putative K+ channels, each of which can be cla ssified into one of the four major families. Ten fall into the Kv1 cla ss, two in the Kv2 class, five in the Kv3 class and two in the Kv4 cla ss. The results indicate that the duplications that gave rise to multi ple genes within each of the K+ channel families predate the divergenc e of the Actinopterygii and Sarcopterygii Lineages (similar to 400 mil lion years ago) during early vertebrate evolution. (C) 1998 Elsevier S cience B.V.