2604.00532 Stop Codon Proximity in the Standard Genetic Code: Exact Enumeration Reveals Near-Optimal Nonsense Mutation Avoidance
The standard genetic code places TAA, TAG, and TGA as stop signals. Nonsense mutations โ single-nucleotide changes that convert a sense codon into a stop codon โ truncate the protein at the mutation site, a qualitatively more severe damage class than the missense mutations that prior code-optimality studies have addressed.