The ATP-binding site of Ca(2+)-ATPase revealed by electron image analysis. |
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| Authors: | K Yonekura D L Stokes H Sasabe and C Toyoshima |
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| Affiliation: | Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan. |
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| Abstract: | The location of the ATP-binding site of a P-type ion pump, Ca(2+)-ATPase from rabbit sarcoplasmic reticulum, was examined by cryoelectron microscopy. A nonhydrolyzable analog of ATP, beta, gamma-bidentate chromium (III) complex of ATP (CrATP), was used to stabilize the enzyme in the Ca(2+)-occluded state. Tubular crystals were then induced by vanadate in the presence of EGTA, keeping CrATP bound to the enzyme. The three-dimensional structures of the crystals were determined at 14 A resolution by cryoelectron microscopy and helical image analysis. Statistical comparison of the structures with and without CrATP showed clear and significant differences at the groove proposed previously as the ATP-binding pocket. |
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