FIG. 3.
Binding of the recombinant proteins GST-VP8, GST-VP5, and GST to MA104 cells. (A) The indicated amounts of affinity-purified GST-VP5 (a), GST-VP8 (b), and GST (c) were incubated with 5 × 104 MA104 cells in suspension for 1 h at 4°C. The amount of cell-bound protein was determined by an ELISA as described in Materials and Methods. The total amount of recombinant protein added to each assay mixture is plotted against the OD405 reading obtained in the ELISA plate. (B) OD readings obtained when the indicated amounts of recombinant proteins were directly assayed in an ELISA. The inset shows the SDS-PAGE analysis of the affinity-purified fusion proteins used in the ELISA and binding assays. MW, molecular weight in thousands.