Microtubules are dynamic structures assembled from heterodimer subunits of alpha and beta tubulin proteins, which have important roles in eukaryotic cell division and intracellular transport. Using GTP as an energy source the microtubules switch between phases of growth and rapid shrinkage in the process of dynamic instability, which is important for microtubule function in vivo. Therefore, drugs which bind tubulin and disrupt microtubule dynamics have been useful in treating cancer and as fungicides. Purified tubulin in vitro also self assembles to form dynamic microtubules. My previous work has shown that the dynamics of microtubules assembled from a purified yeast tubulin are different to those of mammalian tubulins, and we are trying to understand how these differences arise from the limited amino acid changes in tubulin proteins from different species. Yeast cells have many advantages for studying microtubules in vivo and through the development of methods for purification of the yeast tubulin it is also possible to use biochemical and structural methods in vitro. I use a mixture of cell and molecular methods, together with biochemical and microscope-based assays for in vitro analysis of microtubule dynamics.