. 2022 Oct 21;18(10):e1010623. doi: 10.1371/journal.pcbi.1010623

Table 1. System’s initial conditions (IC).

Variable	IC (Molecules/Cell)	References
^†IFN	[5 × 10³, 1 × 10⁴]	Fitted
R2	1000	[56–59]
RC	0	TS
R1	1000	TS
AR	0	TS
STAT1_c	850667	[4, 30, 60, 61]
STAT1_n	0	TS
^‡STAT2_c	9325	[4, 60, 62]
^‡STAT2_n	150	[4, 60, 62]
SOCS	0	[63]
dimerSTAT	0	[64]
IRF9_c	10	[4]
^‡IRF9_n	60	Fitted
ISGF3_c	0	TS
ISGF3_n	0	TS
^‡STAT2-IRF9_c	200	Fitted
^‡STAT2-IRF9_n	325	Fitted
pSTAT1	0	[64]
pSTAT2	0	[64]
IR	0	TS
^‡mIRF9_c	14	Fitted
mIRF9_n	0	TS
mSOCS_c	0 (avg. 0.08)	TS
mSOCS_n	0	TS
mMxA_c	0 (avg. 0.2)	TS
mMxA_n	0	TS
mIFIT1_c	0 (avg. 0.2)	TS
mIFIT1_n	0	TS
^⋆ MxA	1582	Fitted
^⋆IFIT1	705	Fitted
irf9	0	TS
socs	0	TS
ifit1	0	TS
mxa	0	TS
irf9*	0.62	TS
socs*	0.02	TS
mxa*	0.06	TS
ifit1*	0.11	TS
I_irf9	0.38	TS
I_socs	0.98	TS
I_mxa	0.94	TS
I_ifit1	0.89	TS

^† Values for the initial IFN concentration were estimated by fitting the model to the experimental immunoblotting data. Obtaining that 500 U of IFN correspond to 10,000 IFN molecules and 250 U of IFN correspond to 5,000 molecules.

^‡ System’s initial conditions for IRF9_n, mIRF9_c and STAT2-IRF9 complexes as well as localisation distributions of STAT2 were estimated such that the model is in a steady state in absence of interferon under consideration of experimental measurements, information about retention signals and localisation distributions from other groups [4, 5].

^⋆ Values for the initial ISG particle numbers were estimated by fitting the model to the experimental FACS data.

This study (TS) represent values assumed for the simulations: All species which are believed to be inactive in absence of stimulation and are not driving the basal expression were zeroed, while the initial conditions of two-state promoter scheme were set to the unstimulated steady state (just basal expression). The molecule number of R1 was assumed to match the known literature value of R2.