Comparison of the genomic profiles of number of ATGs in the three frames (in black), to the one obtained for randomized genomes (in yellow) with the same proteins, GC content, and codon bias, for four model organisms (<i>S.</i><i>cerevisiae</i>, <i>C. elegans</i>, <i>H. sapiens</i> , <i>S. paradoxus</i>).

<p>A red/green dot corresponds to a position where the number of alternative ATG codons is significantly lower/higher than expected in the randomized genome model (details in the <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003136#s4" target="_blank">Methods</a> section). The figure demonstrates that there is selection for less ATGs (red dots) in the 5′UTR and also at the beginning of the ORF. The positions with more ATGs than expected (green dots) after the beginning of the ORF may be related to yet unknown codon bias signals in that region. See supplementary Figures S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15, S16, S17, S18, S19, S20, S21, S22, S23, S24, S25, S26, S27, S28, S29, S30, S31, S32, S33 for detailed figures of all 33 analyzed organisms, for two types of genome randomizations (<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003136#s4" target="_blank">Methods</a>).