Effects of Activating Mutations on EGFR Cellular Protein Turnover and Amino Acid Recycling Determined Using SILAC Mass Spectrometry

Figure 3

Lysine and arginine recycling in WT EGFR in A431 cells. K and R recycling was calculated by quantifying EGFR peptides with a single missed cleavage from two separate sets of cells, each sample analyzed twice for a total of four MS analyses. The amounts of HH (new peptide), HL (new peptide with recycled amino acid), and LL (old peptide or both amino acids’ recycled peptide) were measured. LL was assumed to be composed of only original peptides for this calculation. Recycling appeared to plateau at or before 48 hours which was not unexpected.