Tug-of-war of microtubule filaments at the boundary of a kinesin- and dynein-patterned surface.

Intracellular cargo is transported by multiple motor proteins. Because of the force balance of motors with mixed polarities, cargo moves bidirectionally to achieve biological functions. Here, we propose a microtubule gliding assay for a tug-of-war study of kinesin and dynein. A boundary of the two motor groups is created by photolithographically patterning gold to selectively attach kinesin to the glass and dynein to the gold surface using a self-assembled monolayer. The relationship between the ratio of two antagonistic motor numbers and the velocity is derived from a force-velocity relationship for each motor to calculate the detachment force and motor backward velocity. Although the tug-of-war involves >100 motors, values are calculated for a single molecule and reflect the collective dynein and non-collective kinesin functions when they work as a team. This assay would be useful for detailed in vitro analysis of intracellular motility, e.g., mitosis, where a large number of motors with mixed polarities are involved.