[1][2] Translation of the uORF typically inhibits downstream expression of the primary ORF.
[3] Approximately 50% of human genes contain uORFs in their 5'UTR, and when present, these cause reductions in protein expression.
[4] Human peptides derived from translated uORFs can be detected from cellular material with a mass spectrometer.
[5] uORFs were found in two thirds of proto-oncogenes and related proteins.
[6] In bacteria, uORFs are called leader peptides and were originally discovered on the basis of their impact on the regulation of genes involved in the synthesis or transport of amino acids.