FIG. 4.

GIT1 association with paxillin LD4 is regulated by PIX binding. (A) Paxillin is immunoprecipitated with C-terminal constructs of GIT1. COS-7 cells were transfected with expression vectors containing Flag-tagged ΔGIT1 constructs depicted in panel C and GFP-paxillin. Western blots (WB) of anti-Flag immunoprecipitates or total lysates (50 μg per lane) were probed by antipaxillin. (The smallest Δ3 GIT1 [residues 646 to 770] is detected in separate gels but not shown here.) (B) Coexpression of PIX potentiates the ability of GIT1 to associate with paxillin. GIT1 or Δ4 and Δ3 represent cotransfection. A significant increase of paxillin (top) associated with Flag-GIT1 immunoprecipitates (IP) (middle) was observed when PIX was also present. Total GFP-paxillin expression is shown at the bottom. (C) Summary of constructs used and their ability to bind paxillin via the conserved C-terminal region (black).