Fig. 6From: Analysis of secondary structural elementsĀ in human microRNA hairpin precursorsThe five most frequently occurring 1Ć1 nucleotide internal loops in human miRNA precursors have different preferences for 5ā and 3ā closing base pairs. Please note that ā5āAUā indicates a 5āAU or 5āUA closing base pair. Likewise, ā5āGCā indicates a 5āGC or 5āCG closing base pair, and ā5āGUā indicates a 5āGU or 5āUG closing base pair. Interestingly, changing the orientation of the loop nucleotides changes closing base pair preferences. For example, in miRNAs, C/A prefers 5ā GCā>āAUā>āGU and 3ā AUā>āGCā>āGU while A/C prefers 5ā AUā>āGCā>āGU and 3ā AUāāāGCā>āGU. The distribution of closing pairs is different for highly expressed human RNAs and RNAs from other organisms. Statistically significant differences were observed for RNAs from other organisms as indicated by *, p <0.05; **, p <0.01; ***, pā<ā0.001Back to article page