The sequence at the 5' end of the messenger RNA that does not code for product. This sequence contains the ribosome binding site and other transcription and translation regulating sequences.

Synonyms: Regions, 5' Untranslated, Untranslated Region, 5', mRNA Leader Sequences, 5' Untranslated Region, mRNA Sequences, Leader, Sequences, Leader mRNA, Region, 5' Untranslated, mRNA Leader Sequence, mRNA Sequence, Leader, 5' UTR, UTRs, 5', Sequence, mRNA Leader, Leader mRNA Sequences, Leader mRNA Sequence, 5' UTRs, 5'UTRs, Sequences, mRNA Leader, Leader Sequence, mRNA, 0, Leader Sequences, mRNA, Sequence, Leader mRNA, 5' Untranslated Regions, UTR, 5', 5'UTR, Untranslated Regions, 5'