Figure 4.

(A). Structure and in vitro synthesis of mRNA. The basic structure of mRNA for therapeutics development. Cap, 5′ UTR, ORF, 3′ UTR, and PolyA are the five structural components of mRNA. (B). In vitro Synthesis of Modified mRNA. Mostly, vector DNA is used to construct the mRNA sequence. RNA polymerase uses the linearized DNA template containing either T7 or T3 or another promoter sequence for in vitro transcription (IVT) of mRNA. In some instances, caping and poly A addition can be done after the IVT process. However, some advanced kits are engineered to do the capping and poly A during the IVT process as a single step. More details are reviewed elsewhere [1].