The preponderance of significant negative correlations with ORF length among eukaryotes is itself highly significant, for both 5′-mRNA folding energy (binomial P < 10 −11 ) and 5′-CAI (binomial P < 10 −9 )—suggesting a systematic eukaryotic trend toward faster translation initiation and faster early elongation in short versus long genes.
Discussion We have reported a strong trend toward weaker 5′-mRNA structure in short genes, when compared with long genes, among eukaryotic species.
We calculated a two-tailed P value to assess whether there is an overall trend in the direction of rank correlation between 5′-mRNA folding energy and coding sequence length.
We report a significant trend toward reduced 5′-secondary structure in shorter coding sequences, suggesting that short genes initiate faster during translation.