THE KCNQ2 POTASSIUM CHANNEL - SPLICE VARIANTS, FUNCTIONAL AND DEVELOPMENTAL EXPRESSION - BRAIN LOCALIZATION AND COMPARISON WITH KCNQ3

Benign familial neonatal convulsions, an autosomal dominant epilepsy o f newborns, are linked to mutations affecting two six-transmembrane po tassium channels, KCNQ2 and KCNQ3. We isolated four splice variants of KCNQ2 in human brain. Two forms generate, after transient expression in COS cells, a potassium-selective current similar to the KCNQ1 curre nt. L735,821, a benzodiazepine molecule which inhibits the KCKQ1 chann el activity (EC50 = 0.08 mu M), also blocks KCNQ2 currents (EC50 = 1 5 mu M). Using in situ hybridization, KCNQ2 and KCNQ3 have been localiz ed within the central nervous system, in which they are expressed in t he same areas, mainly in the hippocampus, the neocortex and the cerebe llar cortex. During brain development, KCNQ3 is expressed later than K CNQ2. (C) 1998 Federation of European Biochemical Societies.