TUBULIN AND MICROTUBULE STRUCTURE

Our knowledge of microtubule structure and its relationship to microtu bule function continues to grow. Cryo-electron microscopy has given us new images of the microtubule polymerization and depolymerization pro cesses and of the interaction of these polymers with motor proteins. W e now know more about the effect of nucleotide state on the structure and dynamic instability of microtubules. The atomic model of tubulin, very recently obtained by electron crystallography, is bringing new in sight into the properties of this protein and its self-assembly into m icrotubules, and promises to inspire new experimental efforts that sho uld lead us to an understanding of the microtubule system at the molec ular level.