Fig. 5: In vitro translation of synthetic proco protein controls.

a Schematic illustrates the design of proco genes that are translated to form protein controls. Trypsin digestion of the proco proteins then liberates control peptides of differing size, charge and retention time, enabling the calibration of LC-MS/MS. b Quantification of each fully cleaved proco peptide. Relative peptide abundance is measured by the proportion of detected peptides relative to all peptides in the proco protein. Data are presented as mean values +/- SD (n = 3 biologically independent samples). c Schematic diagram indicates how peptides are also present at differing copy-number, thereby forming a staggered quantitative reference ladder for evaluating quantitative performance of proteomic experiments. Data plots are for illustrative purposes only, and are not based on Mass Spectrometric measurements. d Measurement of relative peptide abundance for proco proteins and housekeeping E. coli proteins (where each peptide is expected to be in equal abundance) in replicate (n = 3). Source data are provided in a Source Data File.