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Editing by insertion of bases. occurs in mitochondrial genes of trypanosomes and in some viruses (e. g. measles virus). Guide RNAs base-pair with pre-mRNAs then extra bases are inserted. Primary transcript. GAAA A G G C UUUAAC. GAAA A G G C UUUAAC. UUUAAAUAUAAUAGAAAAUUG. Guide RNA.
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Editing by insertion of bases occurs in mitochondrial genes of trypanosomes and in some viruses (e. g. measles virus). Guide RNAs base-pair with pre-mRNAs then extra bases are inserted.
Primary transcript GAAA A G G C UUUAAC GAAA A G G C UUUAAC UUUAAAUAUAAUAGAAAAUUG Guide RNA GAAA UUU A U G UU G U C U UUUAAC Edited mRNA UUUAAAUAUAAUAGAAAAUUG Pairing with guide RNA Insertion of uridines
Old model for mechanism of insertion. A polyU tail on the guide donates uridines to the mRNAs undergoing editing.
Multiple insertions occur until the mRNA matches the guide. This series of reactions is now thought to be an artefact.
Insertion is catalysed by by a complex of an endonuclease, a uridine transferase and an RNA ligase. Precursor Guide Endonuclease
U U Uridine transferase RNA ligase