Proximity of AUG sequences to initiation codon in genomic 5' UTR regulates mammalian protein expression

Protein expression can be controlled via AUG sequences located upstream to the initiation codon in the 5' end untranslated region (5' UTR). Our study was focused on the effect of distance between the initiation codon and the first upstream AUG. An inhibitory effect on protein expression was established when AUG exists in 5' UTR, and this effect is increased when multiple AUG sequences occur there. The study was performed with ATG16L2, a non-lethal gene with no introns or upstream AUG sequence to avoid any interference. New mutations were generated at different locations within the promoter region of ATG16L2 gene and added to a plasmid construct containing a luciferase gene reporter gene. The results show a clear relationship between the distance of the novel AUGs from initiation codon and protein expression. The inhibitory effect was even stronger when multiple AUG sequences were present in 5' UTR.