Fig. 3.

Translational selection against the cost of misfolded proteins can act at two distinct points. mRNA (left) may be translated without errors to produce a folded protein (top); if an error is made, the resulting protein may still fold properly, or may misfold and undergo degradation (right). Selection can act at A to increase the proportion of error-free proteins through codon preference (translational accuracy), and also at B to increase the proportion of proteins that fold despite errors (translational robustness). We neglect misfolding of error-free proteins (see text).