KCNK13

Potassium channel, subfamily K, member 13 (KCNK13), also known as K_2P13.1 or THIK-1, is a protein that in humans is encoded by the KCNK13 gene. It is a potassium channel containing two pore-forming P domains.

K_2P13.1 was first discovered in 2000 from a rat cDNA library, along with the closely related protein K_2P12.1 The two channels were named tandem pore domain halothane-inhibited K⁺ channel 1 and 2 (THIK-1 and THIK-2) because the anesthetic halothane inhibited the potassium current. THIK-1 was also shown to be activated by arachidonic acid and displayed mild voltage dependence, with moderate outward rectification at low external K⁺ and weak inward rectification with nearly symmetrical K⁺ concentrations. Later research showed that THIK-1 can be activated by G-protein-coupled receptor pathways and by polyanionic lipids such as PIP₂ and oleoyl-CoA.

In humans, THIK-1 expression is almost exclusively restricted to microglia, where it functions as the main potassium channel and is responsible for maintaining their resting membrane potential through tonic background potassium conductance. THIK-1 activity can regulate microglial ramification, surveillance, NLRP3 inflammasome activation, and subsequent release of pro-inflammatory cytokine interleukin-1β (IL-1β). It also plays a role in cell shrinkage during apoptosis via caspase-8 cleavage.