FIG. 4.

Replacement of domains M3 and M4 with the SV41 F counterparts does not increase the specificity of M(1+2) for the SV41 HN protein. (A) Schematic diagram of chimeric F proteins. (B) Western blotting of chimeric F proteins was performed as described in the legend to Fig. 3B. (C) Cell surface expression levels and fusion activity of the chimeric F proteins were quantified as described in the legend to Fig. 3C, except that the cell surface expression levels were normalized by the value given by M(1+2).