γ-Tubulin complexes and microtubule nucleation

Microtubules are dynamic cytoskeletal polymers that assemble from alpha/beta -tubulin and are vital for the establishment of cell polarity, vesicle trafficking and formation of the mitotic/meiotic spindle, gamma -Tubulin, a protein related to alpha/beta -tubulin, is required for initiating the polymerization of microtubules in vivo. gamma -Tubulin has been found in two main protein complexes: the gamma -tubulin ring complex and its subunit, the gamma -tubulin small complex. The latter is analogous to the yeast Tub4 complex. In the past year, important advances have been made in understanding the structure and function of the gamma -tubulin ring complex and how it interacts with microtubules.