Coupling of the TCR to integrin activation by SLAP-130/Fyb

SLAP-130/Fyb (SLP-76-associated phosphoprotein or Fyn-binding protein; also known as Fyb/Slap) is a hematopoietic-specific adapter, which associates w ith and modulates function of SH2-containing leukocyte phosphoprotein of 76 kilodaltons (SLP-76). T cells from mice lacking SLAP-130/Fyb show markedly impaired proliferation following CD3 engagement. In addition, the T cell r eceptor (TCR) in SLAP-130/Fyb mutant cells fails to enhance integrin-depend ent adhesion. Although TCR-induced actin polymerization is normal, TCR-stim ulated clustering of the integrin LFA-1 is defective in SLAP-130/Fyb-defici ent cells. These data indicate that SLAP-130/Fyb is important for coupling TCR-mediated actin cytoskeletal rearrangement with activation of integrin f unction, and for T cells to respond fully to activating signals.