3. Glycogen synthase and glycogen phosphorylase are reciprocally regulated in vertebrates by hormones ★糖原磷酸化酶和糖原合成酶的活性均受磷酸化 和脱磷酸( Phosphorylation and dephosphorylation)调控,但作用正好相反 x Hormones like epinephrine(acting on muscle cells) or glucagon(acting on liver cells) will activate protein kinase a, which will lead to phosphorylation modification of both the glycogen phosphorylase(thus activating it and the glycogen synthase(thus inactivating it3. Glycogen synthase and glycogen phosphorylase are reciprocally regulated in vertebrates by hormones • ★糖原磷酸化酶和糖原合成酶的活性均受磷酸化 和脱磷酸（ Phosphorylation and dephosphorylation ）调控，但作用正好相反。 • ★ Hormones like epinephrine (acting on muscle cells) or glucagon (acting on liver cells) will activate protein kinase A, which will lead to phosphorylation modification of both the glycogen phosphorylase (thus activating it) and the glycogen synthase (thus inactivating it)