Physical mapping of potassium channel gene clusters on mouse chromosomes three and six.

Mammalian voltage-gated K channel genes have been divided into four subfamilies (Shaker, Shab, Shal, and Shaw) based on their sequence identity and similarity to related genes in Drosophila. Genetic mapping of the voltage-gated K channel genes has shown that similar multigene clusters exist on mouse Chr 3 and 6 and suggests that the clusters may have arisen through chromosomal duplication. In this report, YAC-based physical maps of the clustered mouse Shaker-like K channel genes have been constructed using restriction endonuclease and yeast chromosome fragmentation approaches. These data define the physical spacing as 5'-Kcna3-(60 kb)-Kcna2-(90 kb)-Kcna8-3' on Chr 3, and as 5'-Kcna6-(80 kb)-Kcna1-(110 kb)-Kcna5-3' on Chr 6, with all genes oriented in a head-to-tail manner within their respective clusters. These detailed physical maps of both K channel gene clusters provide additional support for the idea of an ancient genome tetraploidization event.