Curled microtubules in the presence of GMPCPP and XMAP215.

Looks can be deceiving. According to two articles in this issue, proteins that look like microtubule stabilizing proteins at times do just the opposite, revealing activities that can both build and destroy microtubules.

Originally described as a Xenopus microtubule stabilizing protein, XMAP215 is a defining member of a large family of microtubule-associated proteins. Depletion of XMAP215 or its homologues leads to decreased spindle microtubule length in several systems, including fly, yeast, and worm. On page 349, however, Shirasu-Hiza et al. find that XMAP215 also promotes depolymerization of microtubules stabilized with a nonhydrolyzable GTP analogue (GMPCPP). This destabilizing activity, like its stabilizing activity, is specific to microtubule plus ends. The new work recalls a 10-year-old report demonstrating that XMAP215 has both activities in vitro.

Sirasu-Hiza et al. used EM analysis to reveal a structure that supports...

The Rockefeller University Press
2003
The Rockefeller University Press
2003
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