FIG. 4.
Cell surface binding of SUHV3-HA to MDCK cells expressing CXCR4. (A) Equivalent amounts of soluble SUHV3-HA were incubated with MDCK cells that were either transfected with a plasmid expressing human CXCR4 (+) or mock-transfected (–). Binding of SUHV3-HA to the surface of MDCK cells was detected by western blotting using the anti-HA MAb. Input: One-tenth of the total amount of SUHV3-HA used in each binding reaction was loaded on the gel. (B) The expression of CXCR4 in MDCK-transfected cells was verified by immunoblotting with the 1F8 MAb directed to human CXCR4. Normalization of protein levels in transfected and mock-transfected MDCK cells was performed by testing the cell lysates for the presence of α-tubulin as described in Materials and Methods. The positions of the molecular weight standards (in kDa) are indicated.