Cloning and functional expression of rat ether-à-go-go-like K+ channel genes

Screening of rat cortex cDNA resulted in cloning of two complete and one partial orthologue of the Drosophila ether-à -go-go- like K + channel ( elk ). Northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed predominant expression of rat elk mRNAs in brain. Each rat elk mRNA showed a distinct, but overlapping expression pattern in different rat brain areas. Transient transfection of Chinese hamster ovary (CHO) cells with rat elk1 or rat elk2 cDNA gave rise to voltage-activated K + channels with novel properties. RELK1 channels mediated slowly activating sustained potassium currents. The threshold for activation was at −90 mV. Currents were insensitive to tetraethylammonium (TEA) and 4-aminopyridine (4-AP), but were blocked by micromolar concentrations of Ba 2+ . RELK1 activation kinetics were not dependent on prepulse potential like REAG-mediated currents. RELK2 channels produced currents with a fast inactivation component and HERG-like tail currents. RELK2 currents were not sensitive to the HERG channel blocker E4031.