The L 5′-UTR uAUG suppresses the translation of the first 505 amino acids of L.

A. Schematic of the expression constructs used, where the L 5′-UTR is in its natural context, upstream of sequences encoding the first 505 amino acids of L and is FLAG-tagged at its C-terminus. The length of the 5′-UTR, the L uORF and the L pORF in nucleotides is indicated. B. Western blot analysis indicating that ablating the uAUG in the 5′-UTR of L enhances L (amino acids 1–505) protein expression. Left. Each L construct was coexpressed with GFP-FLAG. Right. Each L construct was coexpressed with VP35-FLAG, which enhances L expression.