Frequencies of the 61 codons at the first translated position for highly translated IGORFs (red) and occasionally translated ones (yellow). Gini indexes that reflect the statistical dispersion of the 61 codons at the first translated position are given for highly and occasionally translated IGORFs in red and yellow, respectively. Gini index values range from zero to one, and high values reflect the fact that the first translated positions are enriched in specific codons, particularly AUG and other NUG ones. Codons that are significantly observed at the first translated position compared with the other translated positions are indicated with a star (one-proportion z-test, P < 5 × 10−2). Near-cognate codons are indicated with diamonds.
