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. Author manuscript; available in PMC: 2022 Jul 6.
Published in final edited form as: Wiley Interdiscip Rev RNA. 2020 May 4;11(6):e1597. doi: 10.1002/wrna.1597

Figure 3. Noncanonical mechanisms of translational enhancement in plant viruses.

Figure 3.

The main protein-coding ORFs of the viral mRNA are represented by a single red box. (A) The viral genome-linked protein Vpg substitutes for a 5’ cap in certain RNA viruses by attracting eIF4E and the cap binding complex to the 5’ end of the viral RNA. (B) Shunting (upper) and reinitiation (lower schematic) of ribosomes on the long 5’ leader of pararetroviruses. For details see text. (C) An internal ribosome entry site in triticum mosaic virus relies on a critical hairpin loop and associated polypyrimidine sequence to attract eIF4G and the ribosome. (D) 3’ cap-independent translational enhancers come in a wide variety of forms. The schematic is not drawn to scale and illustrates shared concepts rather than one specific example. Common elements include 3’ hairpin structures that attract elements of the cap-binding and preinitiation complexes and interact with the 5’ leader of the viral RNA through kissing-loop basepairing interactions. For details see text.