Answer to Question #170756 in Biochemistry for John

Question

A new disease associated with glycogen metabolism has been discovered. It involves a mutation in the glycogen phosphorylase and glycogen synthase enzymes where all of the serine residues in the active and regulatory sites are replaced with glycine residues. Assuming this has no effect on the actual catalytic mechanism of these enzymes describe all of the effects on regulation of glycogen metabolism that would occur.

Answer 1

The liver glycogen is normal in structure but present in abnormally large amounts. The absence of glucose 6-phosphatase in the liver causes hypoglycemia because glucose cannot be formed from glucose 6-phosphate. This phosphorylated sugar does not leave the liver, because it cannot cross the plasma membrane.