Nature Structural & Molecular Biology12, 127 - 132 (2005)
Published online: 23 January 2005; | doi:10.1038/nsmb894
Motility of myosin V regulated by the dissociation of single calmodulin
HoaAnh Nguyen1, 2, 3
& Hideo Higuchi1, 3
1
Center for Interdisciplinary Research, Tohoku University, Sendai 980-8578, Japan.
2
Laboratory of Applied Microbiology, Department of Molecular and Cell Biology, Division of Life Science, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
3
Biomedical Engineering Research Organization, Tohoku University, Sendai 980-8575, Japan.
Myosin V is a calmodulin-binding motor protein. The dissociation of single calmodulin molecules from individual myosin V molecules at 1 M Ca2+ correlates with a reduction in sliding velocity in an in vitro motility assay. The dissociation of two calmodulin molecules at 5 M Ca2+ correlates with a detachment of actin filaments from myosin V. To mimic the regulation of myosin V motility by Ca2+ in a cell, caged Ca2+ coupled with a UV flash system was used to produce Ca2+ transients. During the Ca2+ transient, myosin V goes through the functional cycle of reduced sliding velocity, actin detachment and reattachment followed by the recovery of the sliding velocity. These results indicate that myosin V motility is regulated by Ca2+ through a reduction in actin-binding affinity resulting from the dissociation of single calmodulin molecules.
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M Ca2+ correlates with a reduction in sliding velocity in an in vitro motility assay. The dissociation of two calmodulin molecules at 5 
