Fig. 1

The overhang lengths of miRNA duplexes. The frequency of the overhang lengths of miRNA duplexes: animal miRNAs without human/mouse ones (a), human and mouse non-mirtrons (b) and mirtrons(c). The overhang lengths occurrence of both cleavage sites for animal miRNA duplexes; in each quarter-square the miRBase pre-miRNA structure which leads to the corresponding overhang types is schematically shown (d). Negative values correspond to an atypical 5′ overhangs. The long overhangs on the panel D correspond to structure prediction errors and are described further in the text. These overhangs are not shown on the panels A and C. In mirtron case the splicing overhangs are considered instead of the Drosha ones