Glycogen metabolism Flashcards
Glucagon promotes glygocen _____
breakdown to glucose and release of glucose into the bloodstream
Why is GLUT 4 impt
Insulin dependent found in skeletal muscle and adipose
Once glucose is in cell we_____it, to keep it in the tissue
phosphorolate –>Glucose 6 -phosophate
NADPH is used for ____reactions
anabolic; synthesizes things.
NADH is used for ____things
catabolic; breaking things down
Glycogen is the _____form of glucose and maintains blood glucose and is stored in the ____. It is depleted within
storage; liver; 12-24 hours
fed state–>insulin inc–>
glycogen synthesis
hunger–>glucagon increases–>
glycogen breakdown
What are the 3 enzymes involved in glycogen breakdown
- glygocen phosphorylase
- Debranching enzyme
- Phosphoglucomutase
What is the action of glycogen phosphorylase
cleavess glucose via phosphorolysis sequentially from NR end releasing glucose 1 -phosophate
What is the action of phosphoglucomutase
Converts glucose 1 -phosphate to glucose 6- phosphate
What is the action of debranching enzyme
a bifunctional enzyme. The first action (transferase) transfers 3 glucose residues to main chain. Its second activity (alpha 1-6 glucosidase) is to cleave the next bond and release residue as a free glucose.
Glucose 6-phosphate now needs to be ____to leave the cell.
dephosphorolated; Glucose 6 phosphatase converts glucose 6 phosphate to free glucose in the liver
What are the 3 enzymes required for glycogen synthesis (glycogenesis)
- UDP-glucose pyrophosphorylase
- Glycogen synthase
- Amylo(1–>4) to (1–>6) transglycosylase (glycogen branching enzyme)
What does the UDP carrier molecule provide
Binding oppurtunities which helps to decrease the activation energy and releases PPi which can be hydrolized to provide energy to drive reaction forward.
UDP glucose pyrophosphorylase catalyzes the reaction of glucose 1- phosphate + UTP to
UDP - glucose + PPi
Glycogen synthase adds glucose from UDP-glucose carrier to _____end of growing glycogen chain
non reducing
Glycogen branching enzyme catalyzes the transfer of 6-7 glucose residues from a chain of at least ____ glucose residues long to the C-6 OH group of an interior glucose on the same or nearby chain, thus producing a branch.
11
What is glycogen core
A protein with primer glycogens added. Glycogen synthase cant start from nothing.
Glycogenin provides a _____and is the core protein of glycogen as well as a bifunctional enzyme.
primer;
Glycogen phosphorlylase catalyzes the ____of glycogen and is activated by _____. It is inactivated by phosphoprotein phosphatase 1 (PP1)
breakdown
Glycogen synthase catalyzes the _____of glycogen. It is inactivated by phosphorylation via _____. It is activated by dephosphorylation via _____
synthesis; glycogen synthase kinase.
phosphoprotein phosphatase 1 (PP1)
PKA activates ____which phosphorolates ____
and converts it to phosphorolase a. Now we can breakdown glygcogen to release it in the bloodstream.
phosphorylasekinase; phosphorolate b
The enzyme that phosphoralates Glycogen is called
glycogen synthase kinase. It is a target for Protein Kinase B which is also activated by insulin.
Stopping the inactivation of glycogen by
glycogen synthase kinase and reactivating any inactive glycogen synthase by taking phosphate groups off by PP1
Glucagon activates ___ and favors glycogen breakdown (glycogenolysis)
PKA
Insulin activates ____ and ___ and favors glycogen synthesis
PKB; PP1
