Tubulin and Microtubule Structures

Microtubules are cytoskeletal polymers made of repeating αβ-tubulin heterodimers that play essential roles in all eukaryotic cells. The dynamic character of microtubules is key to their functions, as evidenced by the large number of natural compounds that bind tubulin, alter microtubule dynamics and result in mitotic arrest. The electron crystallographic structure of tubulin showed that the αand βtubulin monomers are very similar. They contain a nucleotide binding domain, an intermediate domain where Taxol binds in β-tubulin, and a C-terminal helical region that form the crest of microtubule protofilaments where motors and other associated proteins bind. The complex dynamic behavior of microtubules, while modulated by other cellular factors, is ultimately due to the tubulin subunit architecture and its intrinsic GTPase activity. Thus, knowledge of the structure of tubulin and the microtubule is essential for our understanding of vital microtubule properties with relevance to broadly used anticancer therapies.