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. Author manuscript; available in PMC: 2016 Aug 16.
Published in final edited form as: RNA Dis. 2016 Jun 6;3(2):e1336. doi: 10.14800/rd.1336

Figure 5. Holo-editosomes include assemblies of auxiliary RNPs and the editing enzyme.

Figure 5

This review focuses on the REH2C subcomplex (with its protein subunits indicated as gray ovals). This subcomplex includes the REH2 helicase, two cofactors (H2F1 and H2F2), and all mRNA types involved in editing (pre-edited, partially edited intermediates, and edited). GRBC* and GRBC are variants of another subcomplex that contains gRNAs and several proteins. These gRNA-bound variants (gRNPs) are distinguished by their content of a protein subunit (3010). REH2C binds to GRBC* via stable contacts (in cis) and to GRBC via transient contacts (in trans). Both types of interaction are via RNA. H2F1 is proposed to recruit mRNA targets for REH2-catalyzed unwinding of localized secondary structure. The relatively disentangled RNA conformers are more likely to anneal with gRNA or undergo editing at individual sites. The preassembled mRNA-gRNA hybrids in the RNP scaffolds can then be processed by the RECC editing enzyme. Thus, the REH2•H2F1 system modulates RNA hybrid quality in assembled RNP scaffolds and the ensuing addition of RECC enzyme in complete holo-editosomes. The initiating gRNA (colored blue) hybridizes to the 3′ most block in the pre-edited mRNA. The mRNAs are shown in red, and the gRNA transcripts are shown in various colors.