Natural frequency (y axis) correlates with the comparative sequence-selection score.

Unique translation initiation sequences demonstrate a relationship between natural frequency and the comparative score. The comparative scoring system was developed to relate unique sequences to their individual nucleotide frequencies relative to the entire population (see text). The exponential function was calculated using the median score from each frequency group, revealing a modest correlation between comparative score and natural frequency. The points are color-coded based on natural frequency. The consensus/canonical Kozak sequence is marked in pink.