Heterotrimeric G proteins and microtubules.

Microtubules, major components of the cytoskeleton, play important roles in a variety of cellular functions including mitosis, intracellular transport, and the modulation of cell morphology. Several studies have demonstrated that specific G-protein alpha subunits bind to tubulin with a high affinity (~130 nM) and elicit various functional effects on tubulin and microtubules. In this chapter, we present a description of the protocols for several methods that are used to determine the interaction between heterotrimeric G proteins and tubulin, as well as functional consequences of the interactions including protocols for protein purification, binding assays, tubulin GTPase assays, microtubule dynamics assays, and assays for cytoskeletal consequences of G-protein-coupled receptor signaling.