4wff

Human TRAAK K+ channel in a K+ bound nonconductive conformation

spinqualitylabelsall models 4wff, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4wff is a 6 chain structure with sequence from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, D10, K Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function KCNK4_HUMAN Voltage insensitive, instantaneous, outwardly rectifying potassium channel. Outward rectification is reversed at high external K(+) concentrations (By similarity). Publication Abstract from PubMed Activation of mechanosensitive ion channels by physical force underlies many physiological processes including the sensation of touch, hearing and pain. TRAAK (also known as KCNK4) ion channels are neuronally expressed members of the two-pore domain K(+) (K2P) channel family and are mechanosensitive. They are involved in controlling mechanical and temperature nociception in mice. Mechanosensitivity of TRAAK is mediated directly through the lipid bilayer--it is a membrane-tension-gated channel. However, the molecular mechanism of TRAAK channel gating and mechanosensitivity is unknown. Here we present crystal structures of TRAAK in conductive and non-conductive conformations defined by the presence of permeant ions along the conduction pathway. In the non-conductive state, a lipid acyl chain accesses the channel cavity through a 5 A-wide lateral opening in the membrane inner leaflet and physically blocks ion passage. In the conductive state, rotation of a transmembrane helix (TM4) about a central hinge seals the intramembrane opening, preventing lipid block of the cavity and permitting ion entry. Additional rotation of a membrane interacting TM2-TM3 segment, unique to mechanosensitive K2Ps, against TM4 may further stabilize the conductive conformation. Comparison of the structures reveals a biophysical explanation for TRAAK mechanosensitivity--an expansion in cross-sectional area up to 2.7 nm(2) in the conductive state is expected to create a membrane-tension-dependent energy difference between conformations that promotes force activation. Our results show how tension of the lipid bilayer can be harnessed to control gating and mechanosensitivity of a eukaryotic ion channel. Physical mechanism for gating and mechanosensitivity of the human TRAAK K+ channel.,Brohawn SG, Campbell EB, MacKinnon R Nature. 2014 Dec 4;516(7529):126-30. doi: 10.1038/nature14013. PMID:25471887 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Antibody 3D structures Potassium channel 3D structures 3D structures of non-human antibody

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