The function of KCNK4 (potassium two pore domain channel subfamily K member 4, Ensembl gene identifier ENSG00000182450) is as follows. K(+) channel that conducts voltage-dependent outward rectifying currents upon membrane depolarization. Voltage sensing is coupled to K(+) electrochemical gradient in an 'ion flux gating' mode where outward but not inward ion flow opens the gate. Converts to voltage-independent 'leak' conductance mode upon stimulation by various stimuli including mechanical membrane stretch, basic pH, heat and lipids (PubMed:22282805, PubMed:25471887, PubMed:25500157, PubMed:26919430, PubMed:30290154, PubMed:38605031). Homo- and heterodimerizes to form functional channels with distinct regulatory and gating properties (PubMed:26919430). At trigeminal A-beta afferent nerves, the heterodimer of KCNK2/TREK-1 and KCNK4/TRAAK is mostly coexpressed at nodes of Ranvier where it conducts voltage-independent mechanosensitive and thermosensitive currents, allowing rapid action potential repolarization, high speed and high frequence saltatory conduction on myelinated nerves to ensure prompt sensory responses (By similarity). Permeable to other monovalent cations such as Rb(+) and Cs(+) (PubMed:26919430). {ECO:0000250|UniProtKB:G3V8V5, ECO:0000269|PubMed:22282805, ECO:0000269|PubMed:25471887, ECO:0000269|PubMed:25500157, ECO:0000269|PubMed:26919430, ECO:0000269|PubMed:30290154, ECO:0000269|PubMed:38605031}.