Glycogenolysis

breakdown of glycogenbreakdownglycogen degradationglycogenolyticliver glucose reserves as a fuel sourceliver's glucose production
Glycogenolysis is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1).wikipedia
103 Related Articles

Glucose 1-phosphate

glucose-1-phosphatebeta-D-glucose 1-phosphateCori ester
Glycogenolysis is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1).
In glycogenolysis, it is the direct product of the reaction in which glycogen phosphorylase cleaves off a molecule of glucose from a greater glycogen structure.

Glycogen phosphorylase

Liver glycogen phosphorylaseliver glycogenliver phosphorylase
Glycogen branches are catabolized by the sequential removal of glucose monomers via phosphorolysis, by the enzyme glycogen phosphorylase. Here, glycogen phosphorylase cleaves the bond linking a terminal glucose residue to a glycogen branch by substitution of a phosphoryl group for the α[1→4] linkage.
Glycogen phosphorylase catalyzes the rate-limiting step in glycogenolysis in animals by releasing glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond.

Glycogen

glycogen depositsglycogen (n)glycogen deposits
Glycogenolysis is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1).
In response to insulin levels being below normal (when blood levels of glucose begin to fall below the normal range), glucagon is secreted in increasing amounts and stimulates both glycogenolysis (the breakdown of glycogen) and gluconeogenesis (the production of glucose from other sources).

Glycogen debranching enzyme

Debranching enzymeAGLdebrancher enzyme
Glycogen debranching enzyme then transfers three of the remaining four glucose units to the end of another glycogen branch.
A debranching enzyme is a molecule that helps facilitate the breakdown of glycogen, which serves as a store of glucose in the body, through glucosyltransferase and glucosidase activity.

Glucose 6-phosphate

glucose-6-phosphateG6PD-glucose 6-phosphate
Glucose-1-phosphate is converted to glucose-6-phosphate (which often ends up in glycolysis) by the enzyme phosphoglucomutase.
Glucose 6-phosphate is also produced during glycogenolysis from glucose 1-phosphate, the first product of the breakdown of glycogen polymers.

Glycolysis

glycolyticglycolytic pathwayEmbden–Meyerhof pathway
Glucose-1-phosphate is converted to glucose-6-phosphate (which often ends up in glycolysis) by the enzyme phosphoglucomutase. In myocytes (muscle cells), glycogen degradation serves to provide an immediate source of glucose-6-phosphate for glycolysis, to provide energy for muscle contraction.
The liver is also capable of releasing glucose into the blood between meals, during fasting, and exercise thus preventing hypoglycemia by means of glycogenolysis and gluconeogenesis.

Liver

hepaticliver protein synthesislivers
Glycogenolysis takes place in the cells of the muscle and liver tissues in response to hormonal and neural signals.
When needed, the liver releases glucose into the blood by performing glycogenolysis, the breakdown of glycogen into glucose.

Insulin

insulin geneINShuman insulin
Glycogenolysis is regulated hormonally in response to blood sugar levels by glucagon and insulin, and stimulated by epinephrine during the fight-or-flight response.
Glucagon, through stimulating the liver to release glucose by glycogenolysis and gluconeogenesis, has the opposite effect of insulin.

Glucagon

serum glucagon
Glycogenolysis is regulated hormonally in response to blood sugar levels by glucagon and insulin, and stimulated by epinephrine during the fight-or-flight response. Parenteral (intravenous) administration of glucagon is a common human medical intervention in diabetic emergencies when sugar cannot be given orally.
Glucagon generally elevates the concentration of glucose in the blood by promoting gluconeogenesis and glycogenolysis.

Diabetes

diabetes mellitusdiabeticdiabetics
Parenteral (intravenous) administration of glucagon is a common human medical intervention in diabetic emergencies when sugar cannot be given orally.
The progression of prediabetes to overt type 2 diabetes can be slowed or reversed by lifestyle changes or medications that improve insulin sensitivity or reduce the liver's glucose production.

Adrenaline

epinephrineadrenaline junkieadrenalin
Glycogenolysis is regulated hormonally in response to blood sugar levels by glucagon and insulin, and stimulated by epinephrine during the fight-or-flight response.
Binding to α-adrenergic receptors inhibits insulin secretion by the pancreas, stimulates glycogenolysis in the liver and muscle, and stimulates glycolysis and inhibits insulin-mediated glycogenesis in muscle.

Glycogenesis

glycogen synthesisGlycogen biosynthesisglycogenetic
*Glycogenesis

Catabolism

cataboliccatabolizedcatabolize
Glycogen branches are catabolized by the sequential removal of glucose monomers via phosphorolysis, by the enzyme glycogen phosphorylase.

Phosphorolysis

phosphorolytic
Glycogen branches are catabolized by the sequential removal of glucose monomers via phosphorolysis, by the enzyme glycogen phosphorylase.

Residue (chemistry)

residueresidueschemical residue
Here, glycogen phosphorylase cleaves the bond linking a terminal glucose residue to a glycogen branch by substitution of a phosphoryl group for the α[1→4] linkage.

Substitution reaction

substitutionsubstitutedsubstituting
Here, glycogen phosphorylase cleaves the bond linking a terminal glucose residue to a glycogen branch by substitution of a phosphoryl group for the α[1→4] linkage.

Phosphoryl group

phosphorylγ-phosphoryl group
Here, glycogen phosphorylase cleaves the bond linking a terminal glucose residue to a glycogen branch by substitution of a phosphoryl group for the α[1→4] linkage.

Phosphoglucomutase

EC 5.4.2.2EC 5.4.2.3Phosphoglucomutase deficiency
Glucose-1-phosphate is converted to glucose-6-phosphate (which often ends up in glycolysis) by the enzyme phosphoglucomutase.

Hydrolysis

hydrolyzedhydrolysehydrolyze
This exposes the α[1→6] branching point, which is hydrolysed by [[glucosidase|α[1→6] glucosidase]], removing the final glucose residue of the branch as a molecule of glucose and eliminating the branch.

Glucosidases

glucosidaseα[1→6] glucosidase
This exposes the α[1→6] branching point, which is hydrolysed by [[glucosidase|α[1→6] glucosidase]], removing the final glucose residue of the branch as a molecule of glucose and eliminating the branch.

Hexokinase

Hexokinase IVhexokinase-2
The glucose is subsequently phosphorylated to glucose-6-phosphate by hexokinase.

Muscle

musclesmuscularmusculature
Glycogenolysis takes place in the cells of the muscle and liver tissues in response to hormonal and neural signals.

Fight-or-flight response

stress responsefight or flightfight-or-flight
Glycogenolysis is regulated hormonally in response to blood sugar levels by glucagon and insulin, and stimulated by epinephrine during the fight-or-flight response. In particular, glycogenolysis plays an important role in the fight-or-flight response and the regulation of glucose levels in the blood.

Myocyte

muscle fibermuscle cellmuscle cells
In myocytes (muscle cells), glycogen degradation serves to provide an immediate source of glucose-6-phosphate for glycolysis, to provide energy for muscle contraction.

Hepatocyte

hepatocytesliver cellsliver cell
In hepatocytes (liver cells), the main purpose of the breakdown of glycogen is for the release of glucose into the bloodstream for uptake by other cells.