Vale, R.D., Funatsu, T., Pierce, D.W., Romberg, L., Harada, Y., Yanagida, T. (1996). Direct observation of single kinesin molecules moving along microtubules.  Nature 380(6573): 451--453.

FBrf0089152

Research paper

Kinesin is a two-headed motor protein that powers organelle transport along microtubules. Many ATP molecules are hydrolysed by kinesin for each diffusional encounter with the microtubule. Here we report the development of a new assay in which the processive movement of individual fluorescently labelled kinesin molecules along a microtubule can be visualized directly; this observation is achieved by low-background total internal reflection fluorescence microscopy in the absence of attachment of the motor to a cargo (for example, an organelle or bead). The average distance travelled after a binding encounter with a microtubule is 600 nm, which reflects a approximately 1% probability of detachment per mechanical cycle. Surprisingly, processive movement could still be observed at salt concentrations as high as 0.3 M NaCl. Truncated kinesin molecules having only a single motor domain do not show detectable processive movement, which is consistent with a model in which kinesin's two force-generating heads operate by a hand-over-hand mechanism.

PMC2852185 (PMC) (EuropePMC)