Assaying microtubule nucleation by the γ-tubulin ring complex.

Microtubule organization by microtubule-organizing centers such as the centrosome requires γ-tubulin, which exists in the γ-tubulin ring complex (γTuRC) that nucleates microtubules. The γTuRC is a ring-shaped, macromolecular complex whose core components are γ-tubulin and the γ-tubulin complex proteins. Despite the recent identification of additional γTuRC components, the molecular composition and regulatory properties of the complex remain poorly understood. The ability to purify the γTuRC at a large scale for characterization may hold a key to understanding the mechanism by which the γTuRC nucleates microtubules. In this chapter, we describe methods to isolate the γTuRC from human cell cultures and to perform assays on the purified γTuRC.