Fig. 4.

Closed mRNA loop model. (a) In vitro transcribed mRNA (IVT-mRNA) can recruit translation initiation factors which bind to the 5'-cap and 5'-untranslated region (5'-UTR), promoting mRNA entry into the ribosome and mRNA translation and also recruit the poly(A)-binding protein (PABP) to the poly(A)-tail; (b) in the closed loop model, strong interaction between the translation factors on both sides of the mRNA induces the formation of a stable loop, which protects the transcripts from RNA degrading enzymes and facilitates mRNA reentry into the ribosome thereby enhancing translation [22].