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Two microtubules means one-way movement

Tagged Eg5 tetramers (white) move directionally where microtubules overlap (between red dotted lines).

For the microtubule motor Eg5, binding two microtubules gives it direction, say Kapitein et al.

Eg5, the vertebrate form of kinesin-5, moves along microtubules either randomly or directionally. In other kinesins, directionality is triggered when the motor binds to its cargo and to the microtubule track. But for Eg5, microtubules are both the track and the cargo, as both ends of the motor protein bind microtubules.

The authors showed that Eg5 moved predominantly randomly when bound to only one microtubule, but switched solely to plus end–directed movement when a second microtubule bound.

Eg5 is one of the main organizers of microtubules in the mitotic spindle, and its ability to slide antiparallel fibers along one another is crucial for pushing opposite poles apart. Alternatively, when encountering parallel fibers, it can "zip them together" if they are skewed, says co-PI Tarun Kapoor. He thinks the ability to move randomly on a single microtubule allows Eg5 to "explore" its environment for another microtubule, "dramatically increasing the efficiency of crosslinking."

Kapitein, L.C., et al. 2008. J. Cell Biol. doi:10.1083/jcb.200801145.[Abstract/Free Full Text]

Richard Robinson

rrobinson{at}nasw.org

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This Article Full Text (PDF, 1218K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Robinson, R. Search for Related Content PubMed Articles by Robinson, R. Social Bookmarking                            What's this?