5hxe

Structural mechanisms of extracellular ion exchange and induced binding-site occlusion in the sodium-calcium exchanger NCX_Mj soaked with 100 mM Na+ and zero Ca2+

spinqualitylabelsall models 5hxe, resolution 2.29Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5hxe is a 1 chain structure with sequence from Methanocaldococcus jannaschii DSM 2661. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.288Å Ligands: 1PE, CL, MYS, NA, OLC Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Y091_METJA Publication Abstract from PubMed Na+/Ca2+ exchangers use the Na+ electrochemical gradient across the plasma membrane to extrude intracellular Ca2+ and play a central role in Ca2+ homeostasis. Here, we elucidate their mechanisms of extracellular ion recognition and exchange through a structural analysis of the exchanger from Methanococcus jannaschii (NCX_Mj) bound to Na+, Ca2+ or Sr2+ in various occupancies and in an apo state. This analysis defines the binding mode and relative affinity of these ions, establishes the structural basis for the anticipated 3:1 Na+/Ca2+-exchange stoichiometry and reveals the conformational changes at the onset of the alternating-access transport mechanism. An independent analysis of the dynamics and conformational free-energy landscape of NCX_Mj in different ion-occupancy states, based on enhanced-sampling molecular dynamics simulations, demonstrates that the crystal structures reflect mechanistically relevant, interconverting conformations. These calculations also reveal the mechanism by which the outward-to-inward transition is controlled by the ion occupancy, thereby explaining the emergence of strictly coupled Na+/Ca2+ antiport. Mechanism of extracellular ion exchange and binding-site occlusion in a sodium/calcium exchanger.,Liao J, Marinelli F, Lee C, Huang Y, Faraldo-Gomez JD, Jiang Y Nat Struct Mol Biol. 2016 May 16. doi: 10.1038/nsmb.3230. PMID:27183196 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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