KCNK4 (also named TWIK-related arachidonic acid stimulated K⁺ channel, TRAAK or K_2P4.1) is a member of the 2-pore (2P) domain K⁺ channels family that at the moment includes 16 members. These channels show little time- or voltage-dependence and are considered to be “leaky” 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.

K_2P channels are regulated by diverse physical and chemical stimuli including temperature, pH, mechanical stretch, inhalation anesthetics, etc. The channels can then be subclassified based in their specific activators. KCNK4 can be integrated to a K_2P subfamily that includes K_2P2.1 (TREK1) and K_2P10.1 (TREK2) that are activated by intracellular unsaturated fatty acids such as arachidonic acid, lysophosphatidic acid, high intracellular pH and mechanical stretch.

KCNK4 expression is largely confined to the brain in mouse samples while in humans it is also expressed in placenta and to a lesser degree in kidney, small intestine and prostate.