3n5k

Structure Of The (Sr)Ca2+-ATPase E2-AlF4- Form

spinqualitylabelsall models 3n5k, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3n5k is a 2 chain structure with sequence from Oryctolagus cuniculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.2Å Ligands: ACT, ALF, K, MG, TG1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function AT2A1_RABIT This magnesium-dependent enzyme catalyzes the hydrolysis of ATP coupled with the translocation of calcium from the cytosol to the sarcoplasmic reticulum lumen. Contributes to calcium sequestration involved in muscular excitation/contraction (By similarity). Publication Abstract from PubMed The sarco(endo)plasmic reticulum Ca2+- ATPase (SERCA) is a transmembrane ion transporter belonging to the PII-type ATPases. It performs the vital task of re-sequestering cytoplasmic Ca2+ to the sarco-endoplasmic reticulum store, thereby also terminating Ca2+-induced signaling such as in muscle contraction. This article focuses on the transport pathways of Ca2+ and H+ ions across the lipid bilayer through SERCA. The ion binding sites of SERCA are accessible from either the cytoplasm or the SR/ER lumen at a time, and the Ca2+ entry and exit channels are both formed mainly by rearrangements of four N-terminal transmembrane (TM) alpha-helices. Recent improvements in the resolution of the crystal structures of rabbit SERCA1a have revealed a hydrated pathway in the Cterminal TM region leading from the ion binding sites to the cytosol. A comparison of different SERCA conformations reveals that this C-terminal pathway is exclusive to Ca2+- free E2-states, suggesting that it may play a functional role in proton release from the ion binding sites. This is in agreement with molecular dynamics (MD) simulations, mutational studies, and in striking analogy to a similar pathway recently described for the related sodium pump. We therefore suggest a model for the ion exchange mechanism in PII-ATPases including not only one, but two cytoplasmic pathways working in concert. Ion pathways in the sarcoplasmic reticulum Ca2+-ATPase.,Bublitz M, Musgaard M, Poulsen H, Thogersen L, Olesen C, Schiott B, Morth JP, Moller JV, Nissen P J Biol Chem. 2013 Feb 11. PMID:23400778 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also ATPase 3D structures

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