A PLCδ₁-binding protein, p122RhoGAP, is localized in focal adhesions

We have investigated the cellular distribution of p122RhoGAP, a GTPase-activating protein of Rho small GTPase and an activator of phospholipase C-δ₁. Immunofluorescence studies demonstrated that endogenous p122 is localized at the tips of actin stress fibres and co-localizes with vinculin in normal rat kidney cells. In immunoprecipitation studies, p122 co-precipitated with vinculin, indicating that p122 is localized at the sites of focal adhesion. We have also shown that the N-terminal half of p122 is responsible for this localization. It is conceivable, therefore, that p122 is involved in the reorganization of the actin cytoskeleton and focal adhesions that regulate cell–substratum adhesion and cell migration.