Regulation of inositol lipid kinases by Rho and Rac

Rho and Rac small GTPases associate with type-I phosphatidylinositol 4-phosphate 5-kinase to regulate the production of phosphatidylinositol 4,5-bisphosphate. This lipid appears to mediate some of the effects of Rho and Rac on the actin cytoskeleton. The genes for several type-I phosphatidylinositol 4-phosphate 5-kinases have been cloned recently but it is not known which one interacts with Rho and/or Rac. Rho family GTPases also interact with phosphatidylinositol 3-kinase, though this kinase can be either upstream or downstream of the GTPases depending upon the system.