leader sequencea sequence of NUCLEOTIDES at the 5'-END of MESSENGER RNA (and on DNA), UPSTREAM of the start CODON for TRANSLATION. This sequence contains the RIBOSOME BINDING SITE but is not normally translated into a part of the PROTEIN of the GENE. In some cases it contains a regulatory region called an ATTENUATOR.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005