FIG. 3.

Specific binding of MV-N to a protein receptor distinct from FcγRII. (A) Requirement of protein synthesis for recovery of MV-N-binding activity after protease treatment. TEC were untreated (left panel) or treated with pronase (middle panel) before MV-N binding. Pronase-treated TEC were incubated for 4 h at 37°C in the absence (gray histogram) or in the presence of cycloheximide (thin line), prior to MV-N binding (right panel). As a negative control, cells were incubated with specific anti-MV-N (Cl25) MAb and streptavidin-PE in the absence of MV-N (dotted line). (B) Dose-dependent binding of FITC-labeled MV-N. TEC were incubated 1 h at 4°C with various amounts of FITC-MV-N, followed by extensive washes prior to flow cytometry analysis. (C) Competition between unlabeled MV-N and FITC-MV-N. Cells were incubated with FITC-MV-N (2.5 μg/well, corresponding to 50% of binding) and increasing amounts of unlabeled MV-N. Percentages of labeled MV-N binding were reported and calculated assuming that the MFI observed with FITC-MV-N alone is 100%. The results are representative from one of three independent experiments.