CLONING AND TISSUE DISTRIBUTION OF 2 NEW POTASSIUM CHANNEL ALPHA-SUBUNITS FROM RAT-BRAIN

The expressed sequence tag (EST) database is a valuable tool to identi fy functionally related clones, when sequence similarity is so low tha t standard Library screening methods cannot be successfully applied. C omparing conserved protein sequences of cloned voltage-gated potassium channels led to the identification and cloning of a new putative pota ssium channel alpha-subunit from rat brain, Kv9.1. A homologue of this cu-subunit was also found in human brain tissue. A second a-subunit, Kv9.3, most probably belonging to the same subfamily, was also isolate d and sequenced. Tissue distribution and analysis of genomic DNA were performed for both channels. rKv9.1 is expressed exclusively in the ce ntral nervous system, whereas rKv9.3 shows a widespread tissue distrib ution. No currents could be measured in X. oocytes upon injection of r Kv9.1 or rKv9.3 cRNA. (C) 1998 Academic Press.