Twenty-one-nucleotide and 24-nt long-hairpin-structured intron (lhp intron)–derived siRNAs were bound to AGO1s and AGO4s, respectively. (A) lhp-intron-derived siRNA sequences counted in AGO1 (AGO1a/b/c) libraries. (B) lhp-intron-derived siRNA sequences counted in AGO4 (AGO4a/b and AGO16) libraries. For both A and B, lhp-intron-derived siRNAs associated with AGO1s or AGO4s differ in the bias of their first nucleotide and length. The 21-nt siRNAs mostly beginning with uridine were preferentially bound to AGO1s. In contrast, the 24-nt siRNAs mostly beginning with adenosine were highly enriched in AGO4 proteins. Besides, the 22-nt siRNAs were under-represented in both AGO1 and AGO4 libraries. (A) Adenosine; (U) uridine; (C) cytosine; (G) guanine.
