The plant alpha-glucan phosphorylase, commonly called starch phosphorylase (EC 126.96.36.199), is largely known for the phosphorolytic degradation of starch. Starch phosphorylase catalyzes the reversible transfer of glucosyl units from glucose-1-phosphate to the nonreducing end of alpha-1,4-D-glucan chains with the release of phosphate. Two distinct forms of starch phosphorylase, plastidic phosphorylase and cytosolic phosphorylase, have been consistently observed in higher plants.
Crit Rev Biotechnol. 2009;29(3):214-24. Starch phosphorylase: role in starch metabolism and biotechnological applications.