FIG. 1.

Summary of mutations in the FCV VPg protein and their effects on recovery of virus. The genome organization and coding assignments of the Urbana strain of FCV (GenBank accession no. L40021) are shown. Dipeptide cleavage sites recognized by the virus-encoded cysteine proteinase are indicated. The four tyrosines (numbered according to the VPg protein amino acid sequence) at positions 12, 24, 76, and 104 were changed to alanine in the infectious cDNA clone pQ14. In addition, the tyrosine at position 24 was changed to serine, threonine, or phenylalanine. For each construct, the ability to recover viable virus is indicated by a plus sign and a lethal mutation is indicated by a minus sign. wt, wild type.