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From Proteopedia
Crystal Structure of the SR Calcium Pump with Bound Aluminium Fluoride, ADP and Calcium
Structural highlights
FunctionAT2A1_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). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedP-type ion transporting ATPases are ATP-powered ion pumps that establish ion concentration gradients across biological membranes. Transfer of bound cations to the lumenal or extracellular side occurs while the ATPase is phosphorylated. Here we report at 2.3 A resolution the structure of the calcium-ATPase of skeletal muscle sarcoplasmic reticulum, a representative P-type ATPase that is crystallized in the absence of Ca2+ but in the presence of magnesium fluoride, a stable phosphate analogue. This and other crystal structures determined previously provide atomic models for all four principal states in the reaction cycle. These structures show that the three cytoplasmic domains rearrange to move six out of ten transmembrane helices, thereby changing the affinity of the Ca2+-binding sites and the gating of the ion pathway. Release of ADP triggers the opening of the lumenal gate and release of phosphate its closure, effected mainly through movement of the A-domain, the actuator of transmembrane gates. Lumenal gating mechanism revealed in calcium pump crystal structures with phosphate analogues.,Toyoshima C, Nomura H, Tsuda T Nature. 2004 Nov 18;432(7015):361-8. Epub 2004 Sep 26. PMID:15448704[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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