Origin of tradeoff between movement velocity and attachment duration of kinesin motor on microtubule

Kinesin-1 motor protein is a homodimer containing two identical motor domains connected together by a common long coiled-coil stalk via two flexible neck linkers. The motor can step on microtubule with a velocity of about 1 μm/s and an attachment duration of about 1 s under the physiological condition. The available experimental data indicated the tradeoff between the velocity and attachment duration under the variation of different experimental conditions, such as the variation of the solution temperature, the variation of the strain between the two motor domains, and so on. However, the underlying mechanism of the tradeoff is unknown. Here, the mechanism is explained by studying theoretically the dynamics of the motor under the variation of different experimental conditions, reproducing quantitatively the available experimental data and providing additional predictions. The origin of the variation of different experimental conditions leading to different decreasing rates of the attachment duration versus velocity is also explained.