Upstream open reading frame

An upstream open reading frame (uORF) is an open reading frame (ORF) within the 5' untranslated region (5'UTR) of an mRNA. uORFs can regulate eukaryotic gene expression. Translation of the uORF typically inhibits downstream expression of the primary ORF. However, in some genes such as yeast GCN4, translation of specific uORFs may increase translation of the main ORF. == In humans == Approximately 50% of human genes contain uORFs in their 5'UTR, and when present, these cause reductions in protein expression.

Source: Wikipedia — Upstream open reading frame (CC BY-SA 4.0)