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Potassium channels are the most widely distributed type of ion channel found in virtually all organisms. [ 1] They form potassium -selective pores that span cell membranes. Potassium channels are found in most cell types and control a wide variety of cell functions. [ 2][ 3]
Structure of the KcsA potassium channel ().The two gray planes indicate the hydrocarbon boundaries of the lipid bilayer and were calculated with the ANVIL algorithm. [5]There are two distinctive features of ion channels that differentiate them from other types of ion transporter proteins: [4]
Voltage-gated ion-channels are usually ion-specific, and channels specific to sodium (Na +), potassium (K +), calcium (Ca 2+), and chloride (Cl −) ions have been identified. [1] The opening and closing of the channels are triggered by changing ion concentration, and hence charge gradient, between the sides of the cell membrane. [2]
structure summary. Voltage-gated potassium channels ( VGKCs) are transmembrane channels specific for potassium and sensitive to voltage changes in the cell's membrane potential. During action potentials, they play a crucial role in returning the depolarized cell to a resting state.
Inward-rectifier potassium channels ( Kir, IRK) are a specific lipid-gated subset of potassium channels. To date, seven subfamilies have been identified in various mammalian cell types, [ 1] plants, [ 2] and bacteria. [ 3] They are activated by phosphatidylinositol 4,5-bisphosphate ( PIP 2 ).
Each inward-rectifier potassium channel α-subunit is composed of two transmembrane α-helices, a pore helix and a potassium ion selectivity filter sequence and assembles into a tetramer forming the complete channel. [3] The two-pore domain potassium channels instead are dimers where each subunit is essentially two α-subunits joined together. [4]
hERG (the human Ether-à-go-go-Related Gene) is a gene that codes for a protein known as K v 11.1, the alpha subunit of a potassium ion channel.This ion channel (sometimes simply denoted as 'hERG') is best known for its contribution to the electrical activity of the heart: the hERG channel mediates the repolarizing I Kr current in the cardiac action potential, which helps coordinate the heart ...
KcsA was the first potassium ion channel to be characterized using x-ray crystallography by Roderick MacKinnon and his colleagues in 1998. In the years leading up to this, research on the structure of K + channels was centered on the use of small toxin binding to reveal the location of the pore and selectivity filter among channel residues.