Glycogen Metabolism Flashcards
What enzyme links glucose molecules together?
glycogen synthase
Whihc enzyme lyses glycogen and converts it to G-1-P?
glycogen phosphorylase
The which enzyme releases a free glucose?
debranching enzyme (alpha-1,6- glucosidase)
Glycogenin is attached to which end of the glycogen chain?
Reducing end
Which end are glucose molecules added to?
Nonreducing end
What enzyme transfers the 4 glucoses on the branched chain onto the core chain of glycogen?
4:4 transferase
The last unit on the branch is hydrolyzed by which enzyme thereby releasing free glucose?
alpha-1,6-glucosidase
In the liver, what is the fate of the G-1-P units?
Converted to free glucose to maintain blood glucose levels
In the muscle, what is the fate of the G-6-P units?
Used in glycolysis to produce ATP for contraction
What tissue does Ca-calmodulin work in?
Muscle
What does Ca-calmodulin activate?
Phosphorylase kinase which stimulates glycogenolysis
What enzyme is the key regulatory enzyme in glycogenolysis?
glycogen phosphorylase
What is the rate limity enzyme in glycogen synthesis?
Glycogen synthase
What does protein kinase A do to glycogen synthase?
Turns it off—-> decreases glycogen synthesis
What does protein kinase A do to glycogen phosphorylase?
Turns it on—-> increases lysis
What does glucagon(liver) and epinephrine (liver + muscle) do?
Stimulate glycogenolysis
What does insulin (liver + muscle) do?
Stimulate glycogen synthesis
In fed state why does glycogen degradation decrease?
Glucagon is low so cAMP cascade isn’t activated
After a meal why isn’t glycogen degradation stimulated in the muscles?
Low levels of cAMP, AMP, Ca, and epinephrine
What enzyme in lysosomes degrade glycogen into glucose?
alpha-glucosidase
What enzyme converts G-6-P to glucose?
Glucose-6-phosphatase
