Small Conductance Calcium-Activated Potassium Channel 2 (SK2)

Small conductance calcium-activated potassium channel 2 (SK2) is a subtype of SK channels, which are potassium-selective ion channels activated by increases in intracellular calcium concentration. These channels play critical roles in regulating membrane potential and excitability in various cell types, especially neurons and cardiomyocytes. SK2 channels are tetrameric complexes composed of four α-subunits, each containing six transmembrane domains (S1–S6), with a pore-forming loop between S5 and S6 that determines potassium selectivity. Calmodulin (CaM) is constitutively bound, conferring calcium sensitivity. Activation leads to K⁺ efflux, causing membrane hyperpolarization. In neurons, it mediates slow afterhyperpolarization (sAHP) following action potentials, limiting firing frequency. Apamin is a selective blocker.

Channel blocker