Myosin-V makes a random twist as it traverses hand over hand along its actin filament, according to a study by Yasunori Komori, Atsuko Iwane, and Toshio Yanagida (Osaka University, Osaka, Japan).
The transport molecule myosin-V, which bears two actin-binding heads each linked by an arm to a central stalk, carries cargo along the cytoskeletal network. The hydrolysis of ATP drives the lagging head off of actin, but how that head swings around the leading head to rejoin the actin was unknown.
In the new experiments, fluorescently labeled actin filaments bound to an immobilized myosin-V were seen to twist randomly clockwise or counterclockwise during each clamp-release-reclamp cycle. The finding indicates that in the cell, where actin is fixed and myosin is free to twist, the trailing myosin head can swing in either direction as it searches out its next forward binding site.
Yanagida thinks the ability...
