Description
Members of the Rac/Rho subfamily of small GTPases or G-proteins are key regulators of numerous processes related to cytoskeletal dynamics. For example, Rac1/2 and cdc42 (and other closely related members) regulate cell migration, contraction and cell volume, among other features, through the control of the cortical actin cytoskeleton. Cdc42 is furthermore a major player in the establishment of a polarized phenotype in numerous specialized cell types whereas Rac is a critical regulator of NADPH oxidases and concomitant ROS production. In common with most other small G-proteins, cellular Rac and Cdc42 cycle between an inactive GDP-bound and an active GTP bound state. The CRIB domain of the Rac-effector PAK1 discriminates between these two conformations and can be used to isolate active Rac/Cdc42GTP complexes out of cell extracts