Impaired FcR γ-chain tyrosine phosphorylation. Control (WT) or GPI-anchor-deficient (KO) DCs were incubated without (-) or with (+) IgG-ICs and lysed. The FcR γ-chain was immunoprecipitated and was detected by antiphosphotyrosine (anti-pY; top blot) and anti γ-chain (anti-γ; bottom blot) Abs using immunoblotting. Lane 1 indicates unstimulated WT DCs; lane 2, WT DCs stimulated with IgG-ICs; lane 3, unstimulated KO DCs; and lane 4, KO DCs with IgG-ICs. Nonphosphorylated γ-chain migrated around approximately 9 to 10 kDa, typically appearing as a rather blurry band (arrow in bottom blot), phosphorylated γ-chain appeared as 2 bands around 15 kDa (arrows in top blot). IgG-IC-induced FcR γ-chain phosphorylation is impaired in GPI-anchor-deficient cells. Shown is the result of 1 representative experiment of 3.