The five prime untranslated region, also known as 5'UTR, plays an important role in regulating gene expression. It contains sequences that control translation initiation, stability, and mRNA localization. Synonyms for the 5'UTR include the leader sequence, the 5' non-coding region, and the 5' flank. Other terms that are sometimes used include the upstream region, the 5' promoter, and the 5' cap. These synonyms all refer to the same portion of the mRNA molecule that is found upstream of the coding sequence. Their usage may vary depending on the context and the field of study, but they all serve to describe the same important functional element within the mRNA molecule.