Figure 4From: Quantification of the glycogen cascade system: the ultrasensitive responses of liver glycogen synthase and muscle phosphorylase are due to distinctive regulatory designsSimulated results of glycogen cascade system in liver under starved conditions. (A) Fractional modification of enzymes at various concentrations of glucose. The sensitivity of the fractional dose-response curve of glycogen synthase (curve a, ~10.4), phosphorylase (curve b, ~6.2), phosphorylase kinase (curve c, ~1.6), CAPK (curve d, ~1.12) (B) Fractional modification of enzymes at various concentrations of cAMP. The sensitivity of the fractional dose-response curve of glycogen synthase (curve a, ~5.2), phosphorylase (curve b, ~3.1), phosphorylase kinase (curve c, ~1.6), CAPK (curve d, ~1.12) (C) Fractional modification of enzymes at various concentrations of glucose-6-phosphate. The sensitivity of the fractional dose-response curve of glycogen synthase (curve a, ~10.5) and phosphorylase (curve b, ~6.4). (D) Fractional modification of phosphorylase as function of glycogen synthase. The dissociation constant (Kd) of phosphorylase-a binding to glycogen synthase phosphatase is taken as 2 μ M (~1000 fold higher Kd than used to simulate results shown in Fig 3). Appreciable amounts of both glycogen synthase and phosphorylase exist in such a fasted state.Back to article page