TWIK-2, an inactivating 2P domain K+ channel.
We cloned human and rat TWIK-2 and expressed this novel 2P domain K(+) channel in transiently transfected COS cells. TWIK-2 is highly expressed in the gastrointestinal tract, the vasculature, and the immune system. Rat TWIK-2 currents are about 15 times larger than human TWIK-2 currents, but both exhibit outward rectification in a physiological K(+) gradient and mild inward rectification in symmetrical K(+) conditions. TWIK-2 currents are inactivating at depolarized potentials, and the kinetic of inactivation is highly temperature-sensitive. TWIK-2 shows an extremely low conductance, which prevents the visualization of discrete single channel events. The inactivation and rectification are intrinsic properties of TWIK-2 channels. In a physiological K(+) gradient, TWIK-2 is half inhibited by 0.1 mm Ba(2+), quinine, and quinidine. Finally, cysteine 53 in the M1P1 external loop is required for functional expression of TWIK-2 but is not critical for subunit self-assembly. TWIK-2 is the first reported 2P domain K(+) channel that inactivates. The base-line, transient, and delayed activities of TWIK-2 suggest that this novel 2P domain K(+) channel may play an important functional role in cell electrogenesis.
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CHEMICAL CHEMICAL GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-Y CHEMICAL GENE-Y GENE-N GENE-Y GENE-Y GENE-N GENE-Y GENE-Y GENE-Y GENE-Y CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL
cysteine K+ 2P domain K(+) channel TWIK-2 2P domain K(+) channel TWIK-2 Rat TWIK-2 TWIK-2 human TWIK-2 TWIK-2 K(+) TWIK-2 2P domain K(+) channel TWIK-2 TWIK-2 M1P1 external loop TWIK-2 TWIK-2 TWIK-2 2P domain K+ channel K(+) K(+) K(+) K(+) K(+) Ba(2+) quinine quinidine