Data were collected using a 15 minute gradient (Table ) on a Xevo TQS (Waters, UK) triple quad mass spectrometer. Targeted method development, initial instrument acquisition file creation, collision energy optimization and fragment selection were all performed using Skyline (v23.1.0.455) (Table -S11). 'Quantotypic' target peptides were selected which were found to be unique to the mammalian Uniprot database.