Fig. 1: Resource load imposed by synthetic constructs can be measured by co-transfection with a transient capacity monitor.

a A transiently expressed fluorescence-based capacity monitor can be used to measure the usage of gene expression resources by a competing co-transfected test plasmid in mammalian cells. b Modular library of synthetic constructs for transient EGFP production developed by varying different construct constituents (promoters, Kozaks and polyAs). Individual plasmids were co-transfected with a CMV-mKATE capacity monitor in HEK293T and CHO-K1. Intracellular fluorescence was measured 48 h post-transfection using flow cytometry. c Response of the capacity monitor to resource loading by synthetic designs with increasing complexity in HEK293T and CHO-K1. An empty plasmid (i), a construct constitutively expressing the rtTA transactivator (ii) and the TET-ON inducible system without (iii) and with (iv) dox addition (1 ng/μl) were considered. Capacity monitor expression is reported as mKATE mean RFU ± standard deviation. Number of biological repeats for each sample is reported in Supplementary data file 3. Two sided Mann–Whitney test P-value: ****<0.0001, ***<0.0005, **<0.005, *<0.05. Exact P-values can be found in Supplementary data file 4. Data analysis is described in the methods section and Supplementary Note 1. Source data are provided in the Source Data file.