Figure 5: Effect of synonymous codons on the folding (structure) of mRNA and coded peptides. A peptide consists of 6R (positively charged, red) and 6E (negatively charged, blue) amino acid residues. It contains reactive termini that interact with each other. This peptide has many equally possible and favored configurations (tertiary structure) and several copies might interact with each other (quaternary structure), for example a compact, globular, configuration that forms dimers (a). However its mRNA may contain structural information simply by replacing AGA with its synonymous codon (cGc). This structural information can be transferred into the peptide during translation and defines different 3D structures and interactions (b, c). A hairpin-like structure, for example, “shortcuts” the reactive termini, resulting in only monomer formation (d). Structurally coded parts of sequences are shaded (grey).