Table 1. Table of Model Parameters^a.

parameter		value	units	description
HKtot		100	nM	histidine kinase
RRtot		0–3000	nM	response regulator
Sctot		0–5000	nM	scaffold
Phtot		0–5000	nM	phosphatase
βAS		10	nM s–1	transcription + translation
β0		0.01		leaky promoter activity (1% of total induction)
γ		3.84 × 10–4	s–1	deg/dilution21,27
γssrA		1.5γ	s–1	degradation for ssrA-tagged proteins
n		2		Hill coefficient for antiscaffold activation
KD		1	nM	KD for AS activation
kdephos		0.003	s–1	phosphatase mediated dephosphorylation21
r		2.8 × 10–4	s–1	Decay constant for diffusion of inducer27
Forward and Reverse Reaction Rates
kHKp	kf	0.003	s–1	HK autophosphorylation21
	kr	0.0001	s–1	ref (20)
kcogp	kf	102.1	s–1	cognate HK-RR phosphorylation21
	kr	0.00294	s–1	ref (21)
knoncog	kf	0.0031	s–1 M–1	noncognate HK-RR phosphorylation21
	kr	0.0002	s–1 M–1	ref (21)
kSH3	kf	1 × 105	s–1 M–1	SH3 domain/ligand binding22
	kr	kf:SH3 (0.1 × 10–6)	s–1	KD = 0.1 μM13
kLZX	kf	1 × 105	s–1 M–1	leucine zipper binding
	kr	kf:LZX (0.01 × 10–6)	s–1	KD = 0.01 μM13
kSc:HK	kf	4kf:SH3	s–1 M–1	scaffold binding to HK with 4 SH3 domains
	kr	kr:SH3	s–1
kSc:RR	kf	kf:LZX	s–1 M–1	scaffold binding to RR with 1 LZX domain
	kr	kr:LZX	s–1
kph:RR	kf	1 × 105	s–1 M–1	phosphatase binding to RRp
	kr	1 × 103	s–1
Closed Loop Antiscaffold Interactions
kSc:AS	kf	kf:LZX + kf:SH3	s–1 M–1	scaffold binding to antiscaffold
	kr	0.001kr:LZX	s–1
kAS-SH3	kf	kf:SH3	s–1	antiscaffold binding to Sc:RR complex
	kr	0.001kr:SH3	s–1
kAS-LZX	kf	kf:LZX	s–1 M–1	antiscaffold binding to Sc:HK complex
	kr	0.001kr:LZX	s–1

^aParameters estimated from the literature are cited. Note: In the open loop circuit there is no antiscaffold, so the closed loop antiscaffold interaction rates are all zero.