Anti-KCNN2 (K_Ca2.2, SK2) Antibody

K_Ca2.2 (KCNN2, SK2) is a member of the Ca²⁺-activated K⁺ channel family with small conductance that includes K_Ca2.1 (KCNN1, SK1) and K_Ca2.3 (KCNN3, SK3). The channel is voltage insensitive and is activated by intracellular Ca²⁺ in the submicromolar range. It has, though, a similar topology to that of voltage-dependent K⁺ channels (K_V channels), that is six transmembrane domains and intracellular N- and C-termini. The functional channel of all the K_Ca2 family members is a multimeric protein composed of four pore-forming subunits.

K_Ca2 channels are extremely sensitive to the levels of intracellular Ca²⁺ and concentrations as low as 300-700 nM can open the channels very rapidly (5-15 ms). Hence, the K_Ca2 channels are highly sensitive and fast Ca²⁺ sensors resembling other known Ca²⁺-binding proteins. This type of Ca²⁺-dependent activation is achieved by the constitutive binding of the K_Ca2 channels to calmodulin, a highly expressed Ca²⁺-binding protein via a calmodulin-binding domain situated at the cytoplasmic C-terminus.

Pharmacologically, the K_Ca2 channels are the only known targets of the bee venom toxin Apamin, with K_Ca2.1 being the least sensitive, K_Ca2.2 the most sensitive and K_Ca2.3 showing intermediate sensitivity.

K_Ca2.2 is predominantly expressed in the nervous system although expression in endothelial cells, heart and liver has been described.

K_Ca2.2 is known to be involved in the regulation of neuronal excitability. They do so mainly via a phenomenon known as after hyperpolarization in which K_Ca2 channels open in response to increased intracellular Ca²⁺ concentrations that result from the entry of extracellular Ca²⁺ through voltage-dependent Ca²⁺ channels during action potentials. In this way, K_Ca2 channels effectively form a Ca²⁺-mediated feedback loop.