Compilation and analysis of sequences upstream from the translational start site in eukaryotic mRNAs

TLDR

5′‑noncoding sequences of 211 higher‑eukaryotic mRNAs have been catalogued. In the survey, 95 % of mRNAs use the 5′‑proximal AUG as the initiator, the purine at the −3 position is highly conserved, C dominates positions −1, −2, −4, and −5, yielding a consensus sequence CCGACCAUG, and while most transcripts share 3–4 nucleotides with this motif, only ten match it perfectly.

Abstract

5′-Noncoding sequences have been tabulated for 211 messenger R'JAs from higher eukaryotic cells. The 5′-proximal AUG triplet serves as the initiator codon in 95% of the mRNAs examined. The most conspicuous conserved feature is the presence of a purine (most often A) three nucleotides upstream from the AUG initiator codon; only 6 of the mRNAs in the survey have a pyrimidine in that position. There is a predominance of C in positions −1, −2, −4 and −5, just upstream from the initiator codon. The sequence CCGACCAUG (G) thus emerges as a consensus sequence for eukaryotic initiation sites. The extent to which the ribosome binding site in a given mRNA matches the −1 to −5 consensus sequence varies: more than half of the mRNAs in the tabulation have 3 or 4 nucleotides in common with the CCACC consensus, but only ten mRNAs conform perfectly.