Figure 4.

Model depicting how binding of 14-3-3 inhibits dimeric β₁Pix-GEF activity. Model depicting how binding of 14-3-3β inhibits dimeric β₁Pix-GEF activity. (A) Under basal conditions, the binding of 14-3-3β to β₁Pix is minimal and does not affect its GEF activity. (B) In the presence of agonist, binding of 14-3-3β to β₁Pix through S516 and T526 is increased. 14-3-3β binding may either block the interaction between Rac1 and the DH domain of β₁Pix or induce a conformational change of the DH domain that would interfere with GTP binding (modified from Chahdi and Sorokin, 2008b with permission). As shown, Cdc42 activity could be regulated by monomeric β₁Pix. 14-3-3β is unable to bind monomeric β₁Pix, while binding of 14-3-3β to dimeric β₁Pix results in inhibition of its GEF activity toward Rac1.