Glycogen Metabolism Flashcards
What enzyme is responsible for incorporating glucose molecules into the glycogen chain via α 1,4 linkages?
Glycogen synthase
From what molecule is glucose added to the glycogen chain?
UDP-glucose
Which enzyme is responsible for the interconversion of glucose-6P and glucose-1P?
Phosphoglucomutase
What enzyme is involved in the introduction of α 1,6 branch points into glycogen?
Branching enzyme
What is the primer required to initiate new glycogen synthesis?
Glycogenin
What is glycogenin?
A self glycosylating protein
How does glycogen phosphorylase break α 1,4 bonds?
By phosphorylation
What occurs to the glucose-6P generated from glycogenolysis in muscle?
It enters glycolysis
What occurs to the glucose-6P generated from glycogenolysis in the liver?
It is converted to glucose
How does debranching in glycogenolysis occur?
- Phosphorylase stops cleaving α 1,4 bonds when it is 4 molecules away from a branch point
- Transferase transfers 3 molecules from the branched section to the linear part
- α-1,6-glucosidase cleaves the α 1,6 bond through hydrolysis
How many molecules away from a branch point does glycogen phosphorylase stop cleaving?
4
What enzyme cleaves the α 1,6 bond in glycogenolysis?
α 1,6-glucosidase
What are the key regulatory enzyme of glycogen metabolism?
- Glycogen synthase
- Glycogen phosphorylase
What are the 2 types of control of glycogen metabolism?
- Allosteric
- Hormonal
What allosterically activates glycogen synthase in the liver?
Glucose and glucose-6P
