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Potassium channel Kv1.2, structure in a membrane-like environment. Calculated hydrocarbon boundaries of the lipid bilayer are indicated by red and blue lines.. Potassium channels are the most widely distributed type of ion channel found in virtually all organisms. [1]
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.
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.
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]
Four genes have been identified as members of the K ATP gene family. The sur1 and kir6.2 genes are located in chr11p15.1 while kir6.1 and sur2 genes reside in chr12p12.1. The kir6.1 and kir6.2 genes encode the pore-forming subunits of the K ATP channel, with the SUR subunits being encoded by the sur1 (SUR1) gene or selective splicing of the sur2 gene (SUR2A and SUR2B).
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]
BK channels are also involved in many processes in the body, as it is a ubiquitous channel. They have a tetrameric structure that is composed of a transmembrane domain, voltage sensing domain, potassium channel domain, and a cytoplasmic C-terminal domain, with many X-ray structures for reference.
Simple diagram of a Large Conductance calcium-activated potassium channel (BK). A similar structure can be hypothesized for the other subtypes in this family of channels. Knowing the structure of these channels can provide insight into their function and mechanism of gating. They are made up of two different subunits, alpha and beta.