Glycogen metabolism Flashcards
glucose is linked by _____ and ______ linkages to form glycogen
alpha 1,4 and 1,6
glycogen is stored in ___ and ____
liver; muscle
G1P–>UDPGluc is catalyzed by
UDP-gluc Pyrophosphorylase
The name of the key regulatory enzyme in glycogen synth
glycogen synthase
glucoses are added to the _____ end of the glycogen, one glucose at a time, forming ____ linkage (through glycogen synthase)
non reducing; alpha 1,4
what is the difference between synthethase and synthase?
the latter does not need ATP for energy
how is 1,6 linkage formed?
thru UDP glucose and glycogen synthase, then branching enzyme that transfers 6-7 glucose residues to another glucose
To start a new glycogen molecule, need to start with ___ , that adds on the first 8 glucose residues to itself on Tyr ___
glycogenin; 194
_____ degrades glycogen from nonreducing ends of the molecule into ____
glycogen phosphorylase; glucose 1-P
Gluc1P is converted to ____ by _____
Gluc6P by phosphoglucomutase
G6P forms _____ in the ___
free glucose; liver
in muscle, G6P enters the ____ path to produce energy
glycolytic
glycogen phosphorylase “a” is the ___ form while “b” is the ___ form; the only diff is the presence of ___ on the GPa serine residue
active; inactive; phosphate
the activator of GP in muscle is __, inhibitors are __ and ___
AMP; ATP, G6P
what is the inhibitor of liver GP?
glucose
what is the difference between GSa and GSb?
a is active and unphosphorylated, b is inactive and phosphorylated
In both muscle and liver, glycogen synthase b is activated by _____
G6P
GSa–>GSb mostly by this type of protein kinase:
GSK-3
GSb–>GSa mostly by this type of protein phosphatase
PP1
these hormones signal need for glycogen breakdown; this hormone signals the opposite
epinephrine (muscle) and glucagon (liver); insulin
phosphorylase kinase is activated by ____
calcium
cyclic AMP activates ______, which activates ______, which activates ____ for the breakdown of glycogen
protein kinase a; phosphorylase kinase, phosphorylase a
insulin binding phosphorylates ____, rendering it ___ , meaning glycogen synthase will remain activated. Insulin also activates ____
GSK3; inactive; PP1
Insulin increases the number of this type of glucose transporters
GLUT4
