Trinucleotide preferences and occurrences in coding, intronic, and non-genic DNA.

<p>The right half of the figure shows from top to bottom the occurrence-occurrence R²s for trinucleotides from coding vs. intronic DNA, coding vs. non-genic DNA, and non-genic vs. intronic DNA, as a function of increasing GC content (horizontal axis); flanked to the left by the corresponding preference-preference R²s for off-frame trinucleotides. The figure's left half shows the corresponding slopes. For the top two rows we used human whole-genome coding-region values (and codons were used as “coding-region trinucleotides”); and for the bottom row we used values from the 49%-GC non-genic subgroup.