Analysis of sequence-length dependent effects.

<p>A: Fraction of slow codons () in the initial part of a gene sequence (first 50 amino acid) vs. fraction of slow codons in the rest of the sequence. Inset: Histogram of the ratio of these two fractions of slow codons. B: Dependence of the fraction of slow codons on the sequence length with (black) and without (red) the initial 50 amino acids. C and D: Length-dependence of the mean square deviation of the codon usage in a protein sequence from expected values based on the fitted average, using the abundance data of Ishihama et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0048542#pone.0048542-Ishihama1" target="_blank">[36]</a> (C) and Lu et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0048542#pone.0048542-Lu1" target="_blank">[37]</a> (D).