Fig. 4.—

CUG codon usage at conserved leucine and serine positions. The graph presents the CUG codon usage with respect to alignment position conservation. For each species we determined the percentage of CUG codons at alignment positions with conservation scores of ≥90%, ≥80%, and ≥50% and a window size of 3, respectively, in the concatenated alignment of the 26 motor and cytoskeletal proteins. Red and blue colors denote the percentages of CUG codons present at alignment positions enriched in serines and leucines, respectively. For comparison, we plotted the percentages of CUG codons at positions of the assigned codon translation to the left (% CUG codons at leucine positions for species using the standard code and % CUG codons at serine positions for species using the AYCU) and the percentages of CUG codons present at alignment positions enriched in the respective other amino acid to the right. When considering only highly conserved alignment positions (≥90% conserved) the CUG codon translation assignment is unambiguous. Species using the AYCU are highlighted in bold.