Which one of the following is not a characteristic of phosphoprotein phosphorylase-1 (PP1)?
A)PP1 can be phosphorylated by protein kinase A (PKA).
B)PP1 can dephosphorylate glycogen phosphorylase,glycogen synthase,and phosphorylase kinase.
C)PP1 is allosterically activated by glucose-6-phosphate.
D)PP1 is inhibited by activated glycogen phosphorylase
E)PP1 is phosphorylated by glycogen synthase kinase-3 (GSK3).

Question

Quizplus · Accepted Answer

PP1 is not phosphorylated by glycogen synthase kinase-3 (GSK3). PP1 can phosphorylate and dephosphorylate many proteins involved in glycogen metabolism and is regulated by various factors including allosteric activation by glucose-6-phosphate and inhibition by activated glycogen phosphorylase. It can also be phosphorylated by protein kinase A (PKA), but not by GSK3.

Which One of the Following Is Not a Characteristic of Phosphoprotein