Reproducibility of protein expression in 96-well format. The data are from two experiments of protein expression, purification, and solubility profiling for plate 19. The data demonstrate good reproducibility for identifying soluble proteins in the multigene, multistep experiments. The data on left in 96-well format are ELISA readings of OD (optical density) at 405 nm for the supernatant (soluble fraction) of the expression, each well for one ORF. The maximum OD reading is 4.0. Color coding describes the level of protein expression, where red is for high, orange for medium, and yellow for low. On the right, listed with OD for each soluble protein, is σ which is calculated as the ratio of OD reading for the supernatant (soluble fraction, data shown) to that for pellet (insoluble fraction, data not shown) from the same expression experiment of an ORF. The OD and σ values combined serve as the solubility signature of a protein.