Calcium-activated potassium channel
Encyclopedia
Calcium-activated potassium channels are divided into BK channel
s, IK channels, and SK channel
s based on their conductance (big, intermediate, and small conductance).
This family of ion channel
s is, for the most part, activated by intracellular Ca2+ and contains 8 members. However, some of these channels (the KCa4 and KCa5 channels) are responsive instead to intracellular Na+ and Cl-. Furthermore, the KCa1 family is both Ca2+ and voltage activated, further complicating the description of this family. The KCa channel α subunits have six transmembrane segments similar to the KVs, except KCa1, in which the N-terminus makes a seventh pass across the membrane to end up outside the cell. The α subunits make homo- and hetero-tetrameric complexes.
SK channel
BK channel
BK channels , also called Maxi-K or slo1, are ion channels characterized by their large conductance of potassium ions through cell membranes. These channels are activated by changes in membrane electrical potential and/or by increases in concentration of intracellular calcium ion...
s, IK channels, and SK channel
SK channel
SK channels are a subfamily of Ca2+-activated K+ channels. They are so called because of their small single channel conductance, ~10 pS. SK channels are a type of ion channel allowing potassium cations to cross the cell membrane and are activated by an increase in the concentration of...
s based on their conductance (big, intermediate, and small conductance).
This family of ion channel
Ion channel
Ion channels are pore-forming proteins that help establish and control the small voltage gradient across the plasma membrane of cells by allowing the flow of ions down their electrochemical gradient. They are present in the membranes that surround all biological cells...
s is, for the most part, activated by intracellular Ca2+ and contains 8 members. However, some of these channels (the KCa4 and KCa5 channels) are responsive instead to intracellular Na+ and Cl-. Furthermore, the KCa1 family is both Ca2+ and voltage activated, further complicating the description of this family. The KCa channel α subunits have six transmembrane segments similar to the KVs, except KCa1, in which the N-terminus makes a seventh pass across the membrane to end up outside the cell. The α subunits make homo- and hetero-tetrameric complexes.
Homology classification
Below is a list of the 8 known calcium-activated potassium channel grouped according to sequence homology of transmembrane hydrophobic cores:SK channelSK channelSK channels are a subfamily of Ca2+-activated K+ channels. They are so called because of their small single channel conductance, ~10 pS. SK channels are a type of ion channel allowing potassium cations to cross the cell membrane and are activated by an increase in the concentration of...
- KCa2.x : KCa2.1KCNN1Potassium intermediate/small conductance calcium-activated channel, subfamily N, member 1 , also known as KCNN1 is a human gene encoding the KCa2.1 protein.-Further reading:...
, KCa2.2KCNN2Potassium intermediate/small conductance calcium-activated channel, subfamily N, member 2, also known as KCNN2, is a protein which in humans is encoded by the KCNN2 gene...
, KCa2.3