Related Experiment Video
Updated: Jun 23, 2026

Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs
Published on: May 10, 2018
Point mutations define a sequence flanking the AUG initiator codon that modulates translation by eukaryotic ribosomes
Abstract:
By analyzing the effects of single base substitutions around the ATG initiator codon in a cloned preproinsulin gene, I have identified ACCATGG as the optimal sequence for initiation by eukaryotic ribosomes. Mutations within that sequence modulate the yield of proinsulin over a 20-fold range. A purine in position -3 (i.e., 3 nucleotides upstream from the ATG codon) has a dominant effect; when a pyrimidine replaces the purine in position -3, translation becomes more sensitive to changes in positions -1, -2, and +4. Single base substitutions around an upstream, out-of-frame ATG codon affect the efficiency with which it acts as a barrier to initiating at the downstream start site for preproinsulin. The optimal sequence for initiation defined by mutagenesis is identical to the consensus sequence that emerged previously from surveys of translational start sites in eukaryotic mRNAs. The mechanism by which nucleotides flanking the ATG codon might exert their effect is discussed.
More Related Videos
09:04Studying Ribonucleotide Incorporation: Strand-specific Detection of Ribonucleotides in the Yeast Genome and Measuring Ribonucleotide-induced Mutagenesis
Published on: July 26, 2018
05:48Removal of an Internal Translational Start Site from mRNA While Retaining Expression of the Full-Length Protein
Published on: March 16, 2022
Related Concept Videos
Mutations
Mutations
Initiation of Translation
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
Leaky Scanning
Mutations
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
Point and Frameshift Mutations