FIG. 3.
Cell surface binding of SUWT-HA, SUΔV3-HA, and SUHV3-HA glycoproteins. (A) Samples of culture supernatants containing similar amounts of the SU-HA glycoproteins (inputs) were incubated with HeLa or MDCK cells as described in Materials and Methods. Cells were washed and lysed and the presence in the cell lysates of each SU-HA glycoprotein was detected by western blotting using the anti-HA MAb. Inputs: As control, one-tenth of the total amount of SU-HA used in each binding reaction was loaded on the gel and immunoblotted with the HA-specific MAb. (B) Quantitation of the cell surface binding of the SUWT-HA and SUHV3-HA glycoproteins by cellular ELISA. HeLa cells were incubated with equivalent amounts of each soluble SU-HA protein and the surface levels of the wild-type and chimeric (HV3) SU-HA glycoproteins were quantitated by cellular ELISA as described in Materials and Methods. The values (mean±SD, three independent assays) correspond to the absorbance of each sample at 405 nm. As negative control (–), cells were incubated with the culture supernatant of mock-transfected cells.