Table 2. Components of peptide library constructed to search and analyze tandem mass spectrometry data.

The LEHHHHHHXXX library was separate from the library that contained the entries of the first three rows of the table (see Supplementary file 3 and 4).

Library component	Example peptides (from Figure 2A)	Enables detection of…	Complete peptide list
Any one of 20 canonical amino acids inserted at the UAG codon	LEHHHHHHQGAR	Near-cognate suppression	Supplementary file 3
Any length of C-tail following UAG codon to the next non-UAG stop codon or to 38 amino acids downstream of the UAG codon, whichever came first	ALGDPMVR	Readthrough, frameshifting, and rescue by ArfA or ArfB	Supplementary file 3
AANDENYALDD degradation tag	LEHHHHHHGDAANDENYALDD	Rescue by tmRNA-SmpB	Supplementary file 3
All peptides of form LEHHHHHHXXX, where X is any amino acid	LEHHHHHHQLD	Loss of translational fidelity	Supplementary file 4