Calcium-activated potassium channels are potassium channels gated by calcium, or that are structurally or phylogenetically related to calcium gated channels. They were first discovered in 1958 by Gardos who saw that calcium levels inside of a cell could affect the permeability of potassium through that cell membrane. Then in 1970, Meech was the first to observe that intracellular calcium could trigger potassium currents. In humans they are divided into three subtypes: large conductance or BK channels, which have very high conductance which range from 100 to 300 pS, intermediate conductance or IK channels, with intermediate conductance ranging from 25 to 100 pS, and small conductance or SK channels with small conductances from 2-25 pS.
SK channels are a subfamily of calcium-activated potassium channels. They are so called because of their small single channel conductance in the order of 10 pS. SK channels are a type of ion channel allowing potassium cations to cross the cell membrane and are activated (opened) by an increase in the concentration of intracellular calcium through N-type calcium channels. Their activation limits the firing frequency of action potentials and is important for regulating afterhyperpolarization in the neurons of the central nervous system as well as many other types of electrically excitable cells. This is accomplished through the hyperpolarizing leak of positively charged potassium ions along their concentration gradient into the extracellular space. This hyperpolarization causes the membrane potential to become more negative. SK channels are thought to be involved in synaptic plasticity and therefore play important roles in learning and memory.
Kv7.3 (KvLQT3) is a potassium channel protein coded for by the gene KCNQ3.
SK3 also known as KCa2.3 is a protein that in humans is encoded by the KCNN3 gene.
The transmembrane cation channel superfamily was defined in InterPro and Pfam as the family of tetrameric ion channels. These include the sodium, potassium, calcium, ryanodine receptor, HCN, CNG, CatSper, and TRP channels. This large group of ion channels apparently includes families 1.A.1, 1.A.2, 1.A.3, and 1.A.4 of the TCDB transporter classification.
Calcium-activated potassium channel subunit alpha-1 also known as large conductance calcium-activated potassium channel, subfamily M, alpha member 1 (KCa1.1), or BK channel alpha subunit, is a voltage gated potassium channel encoded by the KCNMA1 gene and characterized by their large conductance of potassium ions (K+) through cell membranes.
Potassium intermediate/small conductance calcium-activated channel, subfamily N, member 4, also known as KCNN4, is a human gene encoding the KCa3.1 protein.
Chloride channel accessory 1 is a protein that in humans is encoded by the CLCA1 gene.
G protein-activated inward rectifier potassium channel 1(GIRK-1) is encoded in the human by the gene KCNJ3.
Potassium channel subfamily K member 4 is a protein that in humans is encoded by the KCNK4 gene. KCNK4 protein channels are also called TRAAK channels.
Calcium-activated potassium channel subunit beta-2 is a protein that in humans is encoded by the KCNMB2 gene.
Calcium-activated potassium channel subunit beta-3 is a protein that in humans is encoded by the KCNMB3 gene.
Potassium 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. KCNN2 is an ion channel protein also known as KCa2.2.
Potassium voltage-gated channel subfamily KQT member 5 is a protein that in humans is encoded by the KCNQ5 gene.
Calcium-activated potassium channel subunit beta-4 is a protein that in humans is encoded by the KCNMB4 gene.
Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 3 is a protein that in humans is encoded by the HCN3 gene.
Potassium channel subfamily K member 17 is a protein that in humans is encoded by the KCNK17 gene.
Potassium channel, subfamily U, member 1, also known as KCNU1, is a gene encoding the KCa5.1 protein.
Potassium channel subfamily T, member 1, also known as KCNT1 is a human gene that encodes the KCa4.1 protein. KCa4.1 is a member of the calcium-activated potassium channel protein family
Potassium channel subfamily T, member 2, also known as KCNT2 is a human gene that encodes the KNa protein. KCNT2, also known as the Slick channel is an outwardly rectifying potassium channel activated by internal raises in sodium or chloride ions.
