TABLE 1.

Parameter values used in endosomal sorting model that are common to all models

Parameter	Description	Base value
Nav	Avogadro's number	6.023 × 1023 #/mol
Vtotal	Total endosomal volume	3 × 10−14 L
η	Ratio of volume in tubular compartments to vesicular compartments	0.67
kst	Tubular sorting rate constant	0.53 min−1
ksv	Vesicular rate constant	0.06 min−1
κ	Partition coefficient accounting for excluded volume in tubules due to ligand size	0.81
ξ	Fraction of internalized ligand nonspecifically endocytosed	0
γ	Transport rate constant of receptors out of vesicular compartment into tubular compartment	1 min−1
kh	Degradation rate constant	0.09 min−1
kx	Recycling rate constant	0.15 min−1
kon	EGF binding rate constant	5 × 107 M−1 min−1*
koff	EGF dissociation rate constant from EGFR	0.5 min−1*
kc	EGF-EGFR/HER2 dimerization rate constant	1 × 10−3 (#/cell)−1 min−1
ku,R1LR2	EGF-EGFR/HER2 uncoupling rate constant	0.1 min−1†
kc,R1E	EGF-EGFR/ERC coupling rate constant	1 × 10−3 (#/cell)−1 min−1
ku,R1E	EGFR-ERC uncoupling rate constant	0.1 min−1
ERCtotal	Total number of ERCs	10,000 #/cell
IR1L	Input flux of EGF-EGFR complexes	Varied
IR1LR2	Input flux of EGF-EGFR/HER2	Varied

All values come from the original ERC sorting model (French and Lauffenburger, 1996), except as noted.

^*Experimentally measured (data not shown).

^†Parameter value from Hendriks et al. (2003a).