Fig. 4. Five-dimensional parameter analysis of an siRNA screen and validation of model predictions for the roles of PSEN2 and ORAI2.

(A to D) Projections of the five-dimensional parameter readout onto the planes of basal cytosolic Ca²⁺ and (A) store-operated Ca²⁺ influx k_SOC, (B) initial ER load Ca²⁺_ER(0), (C) ER Ca²⁺ leak k_ER,leak, and (D) extrusion capacity J_max are shown as log-fold changes relative to control cells, median-centered and normalized per replicate by the SD σ along each dimension. Red data points denote siRNA effects that changed the parameters predominantly along the respective dimension shown in (A), (B), (C), or (D). Parameter changes labeled with the name of the targeted gene were outliers with |σ| > 2.1 or were predicted to have functional changes of |σ| > 1 due to secondary effects or because they were one of a pair of replicates that was below the threshold. Parameter changes further analyzed and discussed in the text are indicated by open red circles and are labeled with emphasis in the projection where the primary change in function was observed. (E and F) FRET ratios showing differences in resting ER Ca²⁺ concentrations in cells when PSEN2 or ORAI2 was knocked down (E; n = 12) or overexpressed (F; n ≥ 22). Shown are Bonferroni-corrected P values from two-tailed Student’s t test; error bars show SEM.