Fig 2.

Positions of SV41 F-derived segments or amino acids in chimeric PIV5 F proteins. (Top) Side views of the F trimers; (bottom) bottom views of the F trimers. The SV41 F-derived segments and amino acids, which are exposed on the trimer surface, are indicated in the colors representing the domains they belong to (Fig. 1B); for simplicity, those in only one monomer are shown. The amino acids shown in black indicate those that intervene among the SV41 F-derived amino acids in chimera no. 36. The figure was prepared with the aid of the Deep View Swiss-Pdb Viewer program on the basis of the crystal structure of the PIV5 (W3A) F-cleavage-site mutant FR3 (Protein Data Bank accession number 2B9B) (40).