FIG. 7.

Proposed model of gRNA maturation. (A) gA6-[14] gRNA with and without a poly(U) tail shown hybridized to the cognate pre-mRNA substrate A6U2. The brackets represent gRNA anchor sequences. (B) Model of complex assembly and gRNA maturation. gRNA is thought to associate with complex I, where one U may be added at the 3′ end. The cognate mRNA may then associate via the gRNA anchor sequence, disrupting the secondary structure of the gRNA. U residues are then added to the gRNA, which form base pairs with the purine-rich region of the pre-edited region. The pre-edited region of the mRNA is represented as a box.