Motility of myosin V regulated by the dissociation of single calmodulin.
Myosin V is a calmodulin-binding motor protein. The dissociation of single calmodulin molecules from individual myosin V molecules at 1 microM Ca(2+) correlates with a reduction in sliding velocity in an in vitro motility assay. The dissociation of two calmodulin molecules at 5 microM Ca(2+) correlates with a detachment of actin filaments from myosin V. To mimic the regulation of myosin V motility by Ca(2+) in a cell, caged Ca(2+) coupled with a UV flash system was used to produce Ca(2+) transients. During the Ca(2+) 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 Ca(2+) through a reduction in actin-binding affinity resulting from the dissociation of single calmodulin molecules.
Nguyen
HoaAnh
H
Center for Interdisciplinary Research, Tohoku University, Sendai 980-8578, Japan.
Higuchi
Hideo
H
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000378:metabolism*; D002417:Cattle; D002645:Chickens; D009068:Movement / Q000187:drug effects; D024701:Myosin Type V / Q000378:metabolism*; D011485:Protein Binding
D002147:Calmodulin; D024701:Myosin Type V; D002118:Calcium