FORCE-VELOCITY RELATIONSHIPS IN KINESIN-DRIVEN MOTILITY

KINESIN is a microtubule-based motor protein that uses energy released from Mg-ATP hydrolysis to generate force for the movement of intracellular membranes towards the fast-growing (plus) ends of microtubule tracks in cells1. Kinesin-driven microtubule movement can be visualized and quantified using light microscope motility assays2-5 but our understanding of how kinesin generates force and motion is incomplete6. Here we report the use of a centrifuge microscope7,8 to obtain force-velocity curves for kinesin-driven motility and to estimate that the maximal isometric force generated per kinesin is 0.12+/-0.03 pN per molecule.