<p>The top 1 percent of Homo sapiens triplex interactions (grades 1–4) were characterized by <b>(A-C)</b> microRNA dinucleotide frequency, <b>(D)</b> microRNA length, and <b>(E-H)</b> single nucleotide frequency, and compared to these same characteristics for all human microRNAs. The percentage of purine content was the largest discriminating factor in predicting triplex formation, with the majority of binding sites having greater than 75% purine or pyrimidine content (A). Higher GC content (B), length between 21 and 25 nucleotides (D), greater than or less than average G or C content (F and G), and lower than average U content (H) also predicted triplex formation.</p
