Fig. 3

Large-scale analysis of viral overprinted genes from the NCBI Nucleotide database. a and b Show counts of the first position at which a directed point mutation can insert a premature stop codon in the overprinted gene without changing the amino acid sequence of the overlapped gene in each gene pair surveyed. Full-size graphs show mutations over the full length of all genes surveyed with a log₂ scale to ensure visibility of bins with low counts. Insets show the first 100 codons of each gene with a linear y axis. a Shows counts without requiring a restriction site change and (b) shows counts with a required restriction site change. c and d Show positions of the first stop codon mutants from (a) and (b) expressed as the ratio of the position of the first codon relative to the total length of the gene in codons. c, as in (a), shows counts without requiring a restriction site change and (d), as in (b), shows counts with a required restriction site change