Calcium ATPase is a member of the P-type ATPases that transport ions across the membrane against a concentration gradient. Here we have solved the crystal structure of the calcium ATPase of skeletal muscle sarcoplasmic reticulum (SERCA1a) at 2.6 A resolution with two calcium ions bound in the transmembrane domain, which comprises ten alpha-helices ...
Calcium ATPase is a member of the P-type ATPases that transport ions across the membrane against a concentration gradient. Here we have solved the crystal structure of the calcium ATPase of skeletal muscle sarcoplasmic reticulum (SERCA1a) at 2.6 A resolution with two calcium ions bound in the transmembrane domain, which comprises ten alpha-helices. The two calcium ions are located side by side and are surrounded by four transmembrane helices, two of which are unwound for efficient coordination geometry. The cytoplasmic region consists of three well separated domains, with the phosphorylation site in the central catalytic domain and the adenosine-binding site on another domain. The phosphorylation domain has the same fold as haloacid dehalogenase. Comparison with a low-resolution electron density map of the enzyme in the absence of calcium and with biochemical data suggests that large domain movements take place during active transport.
Related Citations:
Structural changes in the calcium pump accompanying the dissociation of calcium. Toyoshima, C., Nomura, H. (2002) Nature 418: 605
Structural basis of ion pumping by Ca(2+)-ATPase of sarcoplasmic reticulum. Toyoshima, C., Nomura, H., Sugita, Y. (2003) FEBS Lett 555: 106
Organizational Affiliation:
Institute of Molecular and Cellular Biosciences, The University of Tokyo, Japan. ct@iam.u-tokyo.ac.jp
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