Figure 2

Schematic representation of metabolic Insulin signaling pathway used for the steady state analysis. Nomenclature: I, Insulin; X, unbound surface insulin receptor; XI, unphosphorylated once-bound surface receptor; XIP, phosphorylated once-bound surface receptor; XI₂P, phosphorylated twice-bound surface receptor; X_i represents intracellular receptor pool; XIP_i and XI₂P_i are internalized form of XIP and XI₂P; phosphatase PTP catalyzes the dephosphorylation of AP, XIP, XIP_i and XI₂P_i. A, unphosphorylated IRS-1; AP, phosphorylated IRS-1; B, inactive PI3-kinase; APB, phosphorylated IRS-1 and PI3-kinase complex; CP3, lipid PI[3,4,5]P₃; CP2, lipid PI[4,5]P₂; CP2', lipid PI[3,4]P₂; phosphatase SHIP2 catalyzes dephosphorylation of CP3 to form CP2', phosphatase PTEN catalyzes dephosphorylation of CP3 to form CP2; F, inactive Akt and PKC-ς; FP, phosphorylated Akt and PKC-ς; E₈ dephosphorylates FP; E₆ phosphorylates CP2' to form CP3; FP activates GLUT4 from intracellular location to plasma membrane. G_C and G_M represent GLUT4 in cytoplasm and on plasma membrane respectively. Kd₁ to Kd₃ are dissociation constants; Kd₄ and Kd₅ are distribution coefficients; Km_r, Km, Km₁to Km₈ are Michaelis-Menten constants; k, k_p, k_d, k_s, k₀, k₁ to k₁₃ are reaction rates as shown in the figure.