Schematic illustration of hFcγRIa mutants and expression levels of hFcγRIa and FcR γ-chain in IIA1.6 transfectants. (A) Schematic representation of the cytoplasmic tails of wild-type (WT) and truncated (▵) hFcγRIa -chains. Numbers correspond to amino acid residues counted from the initiating methionine of hFcγRIa. (B) hFcγRIa expression levels in IIA1.6 transfectants. Cells were incubated with immunofluorescence buffer alone (open profiles) or buffer with FITC-labeled CD64-specific MoAb (shaded profiles). Fluorescence was recorded as arbitrary units on a logarithmic scale and plotted against relative cell number. (C) FcR γ-chain expression in IIA1.6 transfectants. Expression was checked by RT-PCR using specific primers. β-Actin RT-PCR served as a control.