KCNK3 (also named TWIK-related acid sensitive K⁺ channel, TASK-1 or K_2P3.1) is a member of the 2-pore (2P) domain K⁺ channels family that includes at least 16 members. These channels show little time- or voltage-dependence and are considered to be “leak” or “background” K⁺ channels, thereby generating background currents which help set the membrane resting potential and cell excitation.

The K_2P channels have a signature topology that includes four transmembrane domains and two pore domains with intracellular N- and C- termini. The functional channel is believed to be a dimer.

K_2P channels are regulated by diverse physical and chemical stimuli including temperature, changes in intracellular pH, mechanical stretch, inhalation anesthetics, etc. The channels can then be subclassified based in their specific activators.

KCNK3 is extremely sensitive to variations in external pH, a drop in pH from 7.7 to 6.7 will be enough to close most KCNK3 channels.

KCNK3 channel distribution is relatively wide with high expression in the brain and heart as well as in the pancreas, kidney and lung.

KCNK3 can exist in the brain either as a homodimer or as a heterodimer with the closely related channel K_2P9.1 (TASK-3).

During periods of high neuronal activity a transient increase in extracellular pH has been recorded. This pH increase may stimulate KCNK3 channel activity and hence enhance outward K⁺ currents. This in turn will decrease excitability in these neurons and work as a feedback mechanism.