Assembly and regulation of γ-tubulin complexes

Microtubules are major constituents of the cytoskeleton in all eukaryotic cells. They are essential for chromosome segregation during cell division, for directional intracellular transport and for building specialized cellular structures such as cilia or flagella. Their assembly has to be controlled spatially and temporally. For this, the cell uses multiprotein complexes containing gamma-tubulin. gamma-Tubulin has been found in two different types of complexes, gamma-tubulin small complexes and gamma-tubulin ring complexes. Binding to adaptors and activator proteins transforms these complexes into structural templates that drive the nucleation of new microtubules in a highly controlled manner. This review discusses recent advances on the mechanisms of assembly, recruitment and activation of gamma-tubulin complexes at microtubule-organizing centres.