Kinesin II is a heterotrimer of two motor proteins and a third non-motor subunit. Le Bot et al. (page ) find that kinesin II is involved in the movement of membranes between the endoplasmic reticulum (ER) and the Golgi, and Tuma et al. (page ) implicate kinesin II in the dispersion of pigment-filled melanosomes, which Xenopus uses to change color.
Kinesin II is also needed for the transport of flagellar proteins and is found on mitotic and neuronal vesicles, so the simple idea that a single kinesin performs a single function seems to be inadequate. How the attentions of a single motor might be divided to more than one site is not known.
Both groups study kinesin II function using dominant negative, “headless” versions of the XKlp3 kinesin II subunit that lack the motor domain. The headless protein does not affect lysosome movements or melanosome aggregation, but markedly reduces...
