CLONING AND FUNCTIONAL EXPRESSION OF RAT CLC-5, A CHLORIDE CHANNEL RELATED TO KIDNEY-DISEASE

We have cloned a novel member of the CLC chloride channel family from rat brain, rCLC-5. The cDNA predicts a 83-kDa protein belonging to the branch including CLC-3 and CLC-4, with which it shares similar to 80% identity. Expression of rCLC-5 in Xenopus oocytes elicits novel anion currents. They are strongly outwardly rectifying and have a conductiv ity sequence of NO3- > Cl- > Br- > I- >> glutamate(-). Although CLC-5 has consensus sites for phosphorylation by protein kinase A, raising t he intracellular cAMP concentration had no effect on these currents. C urrents were also unchanged when rCLC-5 was coexpressed with rCLC-3 an d rCLC-4, either singly or in combination, rCLC-5 is expressed predomi nantly in kidney and also in brain, lung, and liver. Along the nephron , rCLC-5 message is detectable in all tubule segments investigated, bu t expression in the glomerulus and the S2 segment of the proximal tubu le is low.