2oa0
From Proteopedia
Crystal structure of Calcium ATPase with bound ADP and cyclopiazonic acid
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 PubMedThe sarcoplasmic reticulum Ca(2+)-ATPase is essential for calcium reuptake in the muscle contraction-relaxation cycle. Here we present structures of a calcium-free state with bound cyclopiazonic acid (CPA) and magnesium fluoride at 2.65 A resolution and a calcium-free state with bound CPA and ADP at 3.4A resolution. In both structures, CPA occupies the calcium access channel delimited by transmembrane segments M1-M4. Inhibition of Ca(2+)-ATPase is stabilized by a polar pocket that surrounds the tetramic acid of CPA and a hydrophobic platform that cradles the inhibitor. The calcium pump residues involved include Gln(56), Leu(61), Val(62), and Asn(101). We conclude that CPA inhibits the calcium pump by blocking the calcium access channel and immobilizing a subset of transmembrane helices. In the E2(CPA) structure, ADP is bound in a distinct orientation within the nucleotide binding pocket. The adenine ring is sandwiched between Arg(489) of the nucleotide-binding domain and Arg(678) of the phosphorylation domain. This mode of binding conforms to an adenine recognition motif commonly found in ATP-dependent proteins. The molecular basis for cyclopiazonic acid inhibition of the sarcoplasmic reticulum calcium pump.,Moncoq K, Trieber CA, Young HS J Biol Chem. 2007 Mar 30;282(13):9748-57. Epub 2007 Jan 26. PMID:17259168[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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