Calcium control of glycogen metabolism:

As we have seen, in during epinephrine hormonal control or glucagon, dephosphorylated phosphorylase kinase is activated through being phosphorylated through protein kinase. This then activates stimulates glycogen degradation and phosphorylase. Moreover, there is also another way to activate dephosphorylated phosphorylase kinase, at least partially, and which is through a high concentration of Ca²⁺ ions. This is very important in muscle contraction which is triggered when Ca²⁺ is released from the internal store in the sarcoplasmic reticulum. Thus, as well as allosteric control and hormonal control during muscle contraction both of which stimulate glycogen degradation and there is also calcium control.