Block 3 Lecture 5 -- Formation and Degradation of Glycogen Flashcards
glycogen branches every how many residues
8-14
What does the reducing end of glycogen contain
the 1 free anomeric C
What is the branching linkage
alpha1-6
How is glycogen stored
as granules
What are the enzymes of glycogenolysis?
1) GPase
2) Debranching
3) PGM
also G6Pase but only in liver
What are the enzymes of glycogen synthesis?
1) UDP-Glucose Pyrophosphorylase
2) Glycogen Synthase
3) Branching Enzyme
glycogenin is the primin enzyme
Which form of GPase is active?
PO4
Which form of GS is active?
not phosphorylated
Which form of GPK is active?
PO4
2 forms of GPase?
a and b; a is active
GPase action?
generates G1P one at a time from non-reducing end except on short 4-residue branches; requires PLP
What is the RLS is glycogen breakdown?
GPase
Regulation of GPase?
a/b interconversion
allosterics: ATP, G6P, glucose inhibit; AMP activates
Describe action of debranching?
trisaccharide transfer and hydrolysis of remaining residue
What is the action of PGM?
G1P –> G6P or reverse
What is action of UDP-glucose pyrophosphorylase?
G1P + UTP –> UDP-glucose + PPi
What is activity of glycogen synthase?
adds glucose from UDP-glucose to nonreducing end as 1-4 via Sn1
Activity of branching enzyme?
cleaves 6-8 residues from 11-13 residue chain and attaches them 1-6
Action of glycogenin?
glycosylated by tyr glycosyltransferase, then adds up to 7 more glucose units using UDP-glucose
Deficient enzyme in Type 1?
liver G6Pase
What is type 1
von Gierkes
Deficient enzyme in Coris?
debranching
Deficient enzyme in Type IV?
Andersen’s
Deficient enzyme in Type V
muscle GPase
