Human p190A RhoGAP binds eIF3A and exists in a complex with the 48S translational pre-initiation complex (1013.8)

By regulating the actin cytoskeleton Rho GTPases control biological processes such as cell migration, adhesion and polarity. p190A RhoGAP is an important yet poorly understood Rho GTPase regulator. To shed further light on the functions of p190A RhoGAP, we performed mass spectroscopic analysis of associated proteins. Here we report that human p190A, but not its related paralog p190B, forms a stable complex with multiple subunits of the 48S translational pre-initiation complex. Complex formation involves a direct interaction between the first FF domain of p190A and the PCI/PAM domain of eIF3A. This interaction does not appear to be regulated by Y308 phosphorylation, previously found to control the p190A directed cytoplasmic sequestration of TFII-I, but may instead by controlled by phosphorylation of S296 by an as yet unknown protein kinase. Although other reasons for the detected interaction cannot be ruled out, we speculate that p190A RhoGAP may serve as an anchoring protein allowing the localized transla...