mRNA Start Codon (IMAGE) Max-Planck-Gesellschaft Caption This is the mechanism for the recognition of an AUG start codon by the ribosome (blue) in the absence of a Shine-Dalgarno sequence. The correct AUG start codon (green) differs from all other AUG triplets (red) through its position in a single-strand (unstructured) region of the messenger RNA (black). Credit MPI of Molecular Plant Physiology Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.