Label State variable
x1 Ins, insulin input
x2 INSR, concentration of unbound surface insulin receptors
x3 Ins:INSR, concentration of unphosphorylated once-bound surface receptors
x4 Ins2:INSR-P, concentration of phosphorylated twice-bound surface receptors
x5 surface Ins:INSR-P, i.e. concentration of phosphorylated once-bound surface receptors
x6 Intracellular INSR, i.e. concentration of unbound unphosphorylated intracellular receptors
x7 Intracellular Ins2:INSR-P, i.e. concentration of phosphorylated twice-bound intracellular receptors
x8 Intracellular Ins:INSR-P, i.e. concentration of phosphorylated once-bound intracellular receptors
x9 IRS-1, i.e. concentration of unphosphorylated insulin receptor substrate-1
x10 IRS-1-YP, i.e. concentration of tyrosine-phosphorylated IRS1
x11 Unactivated PI3K, i.e. concentration of unactivated PI 3-kinase
x12 IRS-1-YP:PI3K (activated), i.e. concentration of tyrosine-phosphorylated IRS1/activated PI3-kinase complex
Table 1: Definition of variables in the insulin model.