A conformational change in the actin subunit can change the flexibility of the actin filament.
The mechanical properties of F-actin are very significant, given the central structural role played by actin filaments within muscle and the cytoskeleton. We have determined that actin can exist in a state that has a fourfold increase in flexibility over normal F-actin, and nucleotide. Three-dimensional reconstructions from electron micrographs suggest that this increased flexibility arises from a rotation of subdomain-2, the smallest subdomain, of the actin subunit. The modulation of actin's flexibility by Ca2+ and Mg2+ may have important physiological consequences within the cell. Further, since it has been shown that myosin-decorated actin filaments are more flexible than pure F-actin, it is possible that myosin induces this more flexible state in actin.
Orlova
A
A
Department of Cell Biology and Neuroanatomy, University of Minnesota Medical School, Minneapolis 55455.
Egelman
E H
EH
D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure*; D000199:Actins / Q000378:metabolism / Q000648:ultrastructure*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D009038:Motion; D011487:Protein Conformation
D000199:Actins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D008274:Magnesium; D002118:Calcium