Glycogen synthesis and degradation (Homo sapiens)

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122DegradationSynthesisPhosphorylase KinaseSer/Thr protein phosphatase 2ADifferent formsGSK3BPPP2R5EPHKG1PHKA2GBE1PGM1PYGBCALM3PPP2R3AGSK3ACALM2GlycolysisPHKA1Glycogen (n+1)PYGMPPP2R1BPPP2R5DPPP2R2CUDP-glucosePPP2R5BPYG, liver formGlucose 1-phosphatePPP2R4GYGGYS2GYG2PPP2R1APYGLPPP2R2BcAMPPutative hexokinase HKDC1UGP2GlycogenPPP2R5AD-GlucoseGlucose-6-phosphate (2-)AGLPHKBUGP2Glucose-1-phosphateCALM1PYG, brain formPPP2R5CGlycogenPPP2R3BGlycogen (n+1)PHKG2PYG, muscle formPPP2CBHexokinase-1 (Brain)GYS1PPP2CAPPP2R2APYGhexokinaseHexokinase-2 (muscle)Hexokinase-3 Different forms


Glycogen is a very large, branched polymer of glucose residues. Within skeletal muscle and liver glucose is stored as glycogen. In the liver, glycogen synthesis and degradation are regulated to maintain blood-glucose levels as required to meet the needs of the organism as a whole. In contrast, in muscle, these processes are regulated to meet the energy needs of the muscle itself.

Glycogen synthesis is, unlike its breakdown, endergonic. This means that glycogen synthesis requires the input of energy. Energy for glycogen synthesis comes from UTP, which reacts with glucose-1-phosphate, forming UDP-glucose, in reaction catalyzed by UDP-glucose pyrophosphorylase. Glycogen is synthesized from monomers of UDP-glucose by the enzyme glycogen synthase, which progressively lengthens the glycogen chain with (a1->4) bonded glucose. As glycogen synthase can only lengthen an existing chain, the protein glycogenin is needed to initiate the synthesis of glycogen. The glycogen-branching enzyme, amylo (a1->4) to (a1->6) transglycosylase, catalyzes the transfer of a terminal fragment of 6-7 glucose residues from a nonreducing end to the C-6 hydroxyl group of a glucose residue deeper into the interior of the glycogen molecule. The branching enzyme can act upon only a branch having at least 11 residues, and the enzyme may transfer to the same glucose chain or adjacent glucose chains.

Glycogen degradation consists of three steps: (1) the release of glucose 1-phosphate from glycogen, (2) the remodeling of the glycogen substrate to permit further degradation, and (3) the conversion of glucose 1-phosphate into glucose 6-phosphate for further metabolism.

Information partly derived from "Biochemistry" by Stryer and Wikipedia.

Proteins on this pathway have targeted assays available via the CPTAC Assay Portal

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Ontology Terms



  1. Moses SW, Bashan N, Gutman A; ''Glycogen metabolism in the normal red blood cell.''; Blood, 1972 PubMed Europe PMC Scholia
  2. Salway, Jack G; ''Metabolism at a Glance''; John Wiley & Sons, 2016


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121748view11:24, 3 March 2022DeSlremoved empty comments
119104view09:56, 17 June 2021FinterlyAdded ISBN, removed duplicate PublicationXref and fixed BiopaxRef
117146view09:42, 18 May 2021EweitzModified title
113973view06:29, 14 December 2020EgonwAnother clickable pathway
106813view13:29, 17 September 2019MaintBotHMDB identifier normalization
106435view23:24, 28 August 2019KhanspersModified description
105611view04:54, 10 August 2019KhanspersModified description
102318view08:02, 20 December 2018FehrhartChanged title due to overlap with Reactome pathway
97542view14:38, 24 May 2018Jessev1993Added annotated nodes for different forms of hexokinase and PYG
94085view12:36, 18 August 2017DeSlOntology Term : 'glycogen degradation pathway' added !
94084view12:35, 18 August 2017DeSlConnected last line.
93721view13:40, 14 August 2017DeSlChanged IDs for open-forms of several glucoses to closed forms; added glycogen to gluco-6-phos conversion+inhibition by glucose
89807view11:45, 6 October 2016Mkutmonfix description
63201view20:54, 8 May 2013MaintBotUpdating gpml version
45329view20:15, 7 October 2011AlexanderPicoModified description
45324view20:11, 7 October 2011AlexanderPicoOntology Term : 'glycogen metabolic pathway' added !
43019view11:51, 28 May 2011HarmNijveencorrected CAS ID for glucose-6-phospate
41230view23:46, 1 March 2011MaintBotRemoved redundant pathway information and comments
38907view20:41, 24 September 2010AlexanderPico
38906view20:40, 24 September 2010AlexanderPicopathway node, catalysis edges and layout
35631view19:04, 12 February 2010SusanModified description
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35452view11:48, 12 February 2010Andraadded reference
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32124view13:53, 14 August 2009MaintBotFixed group labels
21730view11:32, 14 November 2008MaintBot[[Pathway:Homo sapiens:Glycogen Metabolism]] moved to [[Pathway:WP500]]: Moved to stable identifier
14700view21:06, 23 May 2008KhanspersAdded connectors and metabolites
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13072view11:13, 17 May 2008MaintBotautomated metabolite conversion
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6328view22:17, 22 May 2007Kdahlquistgpml file for [[Human:Glycogen_Metabolism]]

External references


View all...
NameTypeDatabase referenceComment
AGLGeneProduct178 (Entrez Gene)
CALM1GeneProduct801 (Entrez Gene)
CALM2GeneProduct805 (Entrez Gene)
CALM3GeneProduct808 (Entrez Gene)
D-GlucoseMetaboliteHMDB0000122 (HMDB)
GBE1GeneProduct2632 (Entrez Gene)
GSK3AGeneProduct2931 (Entrez Gene)
GSK3BGeneProduct2932 (Entrez Gene)
GYG2GeneProduct8908 (Entrez Gene)
GYGGeneProduct2992 (Entrez Gene)
GYS1GeneProduct2997 (Entrez Gene)
GYS2GeneProduct2998 (Entrez Gene)
Glucose 1-phosphateMetaboliteHMDB0001586 (HMDB)
Glucose-1-phosphateMetabolite59-56-3 (CAS)
Glucose-6-phosphate (2-)MetaboliteCHEBI:75052 (ChEBI)
Glycogen (n+1)Metabolite9005-79-2 (CAS)
GlycogenMetabolite9005-79-2 (CAS)
GlycolysisPathwayWP534 (WikiPathways)
Hexokinase-1 (Brain)ProteinP19367 (Uniprot-TrEMBL)
Hexokinase-2 (muscle)ProteinP52789 (Uniprot-TrEMBL)
Hexokinase-3 ProteinP52790 (Uniprot-TrEMBL) predominant hexokinase in myeloid cells, particularly granulocytes
PGM1GeneProduct5236 (Entrez Gene)
PHKA1GeneProduct5255 (Entrez Gene)
PHKA2GeneProduct5256 (Entrez Gene)
PHKBGeneProduct5257 (Entrez Gene)
PHKG1GeneProduct5260 (Entrez Gene)
PHKG2GeneProduct5261 (Entrez Gene)
PPP2CAGeneProduct5515 (Entrez Gene)
PPP2CBGeneProduct5516 (Entrez Gene)
PPP2R1AGeneProduct5518 (Entrez Gene)
PPP2R1BGeneProduct5519 (Entrez Gene)
PPP2R2AGeneProduct5520 (Entrez Gene)
PPP2R2BGeneProduct5521 (Entrez Gene)
PPP2R2CGeneProduct5522 (Entrez Gene)
PPP2R3AGeneProduct5523 (Entrez Gene)
PPP2R3BGeneProduct28227 (Entrez Gene)
PPP2R4GeneProduct5524 (Entrez Gene)
PPP2R5AGeneProduct5525 (Entrez Gene)
PPP2R5BGeneProduct5526 (Entrez Gene)
PPP2R5CGeneProduct5527 (Entrez Gene)
PPP2R5DGeneProduct5528 (Entrez Gene)
PPP2R5EGeneProduct5529 (Entrez Gene)
PYG, brain formProteinP11216 (Uniprot-TrEMBL)
PYG, liver formProteinP06737 (Uniprot-TrEMBL)
PYG, muscle formProteinP11217 (Uniprot-TrEMBL)
PYGGeneProduct2.4.1.1 (Enzyme Nomenclature) glycogen phosphorylase
PYGBGeneProduct5834 (Entrez Gene)
PYGLGeneProduct5836 (Entrez Gene)
PYGMGeneProduct5837 (Entrez Gene)
Putative hexokinase HKDC1ProteinQ2TB90 (Uniprot-TrEMBL) expression pharynx, thymus, colon, esophagus, and eye tissue
UDP-glucoseMetaboliteHMDB0000286 (HMDB)
UGP2GeneProduct7360 (Entrez Gene)
cAMPMetaboliteHMDB0000058 (HMDB)
hexokinaseGeneProduct2.7.1.1 (Enzyme Nomenclature) glycogen phosphorylase

Annotated Interactions

No annotated interactions

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