Simultaneous coexpression of large numbers of QconCATs. A set of 76 QconCATs were either expressed individually or in a cosynthesis multiplexed reaction (panel A). The individual QconCAT reaction mixtures were pooled, and the yield of QconCATs was either assessed by SRM using the Glu-fibrinopeptide standard or by data dependent, label-free quantification (DDA, based on summed MS1 intensity of unique peptides). The yield of the individual QconCATs was strongly correlated between the two synthetic approaches (panel B, C). The yield of QconCATs, assessed by SRM analysis of the individually synthesized proteins, was also correlated to the quantity of DNA that was used to drive cell-free expression (panel D).