Fig 3.

Nucleotide changes in Y143 codons that result in observed amino acid substitutions. Single nucleotide changes within either of two possible Y143 codons (TAC or TAT) are sufficient to produce Y143H, Y143C, or Y143S substitutions. Two nucleotide changes are required to produce Y143R, Y143G, or Y143A substitutions. Transitions (purine to purine or pyrimidine to pyrimidine changes) and transversions (purine to pyrimidine or pyrimidine to purine) are indicated with thick or thin arrows, respectively. Nucleotides involved in transversions are underlined.