Calcium induced change in three-dimensional structure of thin filaments of rabbit skeletal muscle as revealed by cryo-electron microscopy.
The three-dimensional images of pure actin filaments and the thin filaments reconstituted from rabbit skeletal actin, tropomyosin and troponin were reconstructed from cryo-electron micrographs. The structural difference between on-state thin filaments (in the presence of calcium ions) and that in an off-state (in the absence of calcium ions) was examined carefully by analyzing 50 filaments in each of states. The image analysis using the t-test showed that there is the significant difference between the three-dimensional structure of thin filaments in an on-state and that in an off-state. It was not determined yet whether this change is due to tropomyosin movement or actin transconformation.
Ishikawa
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T
Department of Physics, School of Science, University of Tokyo, Japan.
Wakabayashi
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T
D000199:Actins / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D005583:Fourier Analysis; D005615:Freezing; D008854:Microscopy, Electron; D009132:Muscles / Q000187:drug effects / Q000648:ultrastructure*; D017433:Protein Structure, Secondary; D011817:Rabbits; D014335:Tropomyosin / Q000737:chemistry; D014336:Troponin / Q000737:chemistry
D000199:Actins; D014335:Tropomyosin; D014336:Troponin; D000255:Adenosine Triphosphate; D002118:Calcium