Figure 1.

The presence of Ω reduces the function of the 5′-cap. luc mRNA with either a control 5′-leader or Ω was synthesized in vitro as poly(A)^–, terminating in a poly(A)₅₀ tail, or terminating in the 204 nt TMV 3′-UTR. The mRNAs were synthesized without a cap, with m⁷GpppG (A) or with GpppG (B) and delivered to carrot protoplasts by electroporation. The degree to which the m⁷GpppG or the GpppG structures stimulated expression from the luc mRNAs with either a control 5′-leader or Ω relative to the corresponding uncapped constructs was calculated from the data in Table 1.