Figure 5

Variable fractional levels of active phosphorylase-a and synthase-a in the liver under fasted (glycogen depletion) state. The dissociation constant of phosphorylase-a binding to glycogen synthase phosphatase was varied from 0.002 μ M to no-inhibition (very high Kd), to simulate the metabolic transition from fasted to fed state. The values of dissociation constants (Kd) used are, curve a: 0.002 μ M; curve b, 0.2 μ M; curve c, 2 μ M; curve d, 5 μ M; curve e, 10 μ M; curve f, 20 μ M; curve g, very high dissociation constant (~10⁶). The active fraction of glycogen synthase and phosphorylase coexist in liver in the no-inhibition state (starved condition), while simultaneous activation of phosphorylase and inactivation of synthase is seen in liver in the fed state. The fractional active form of glycogen synthase and phosphorylase varies over a wide range between these operations.