NEW INSIGHTS INTO MICROTUBULE STRUCTURE AND FUNCTION FROM THE ATOMIC MODEL OF TUBULIN

The structure of tubulin has recently been solved by electron crystall ography of zinc-induced tubulin sheets. Because tubulin was studied in a polymerized state, the model contains information on the interactio ns between monomers that give rise to the ap dimer as well as contacts between adjacent dimers that result in the structure of the protofila ment. The model includes the binding site of taxol, an anti-cancer age nt that acts by stabilizing microtubules. The present tubulin model gi ves the first structural framework for understanding microtubule polym erization and its regulation by nucleotides and anti-mitotic drugs at the molecular level.