Glycogen metabolism (WP1189)

Canis familiaris

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].


Alex Pico , Christine Chichester , Martina Summer-Kutmon , and Eric Weitz


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Canis familiaris



Pathway Ontology

glycogen metabolic pathway


Label Type Compact URI Comment
cAMP Metabolite hmdb:HMDB0000058
UDP-glucose Metabolite hmdb:HMDB0000286
Glucose 1-phosphate Metabolite hmdb:HMDB0001586
PYGM GeneProduct ncbigene:611078
PPP2CB GeneProduct ncbigene:482873
PHKB GeneProduct ncbigene:478139
GYS2 GeneProduct ncbigene:403737
PPP2R5B GeneProduct ncbigene:483755
PHKG2 GeneProduct ncbigene:607275
PPP2R5C GeneProduct ncbigene:480436
CALM1 GeneProduct ncbigene:480416
PHKA1 GeneProduct ncbigene:491956
PPP2R2C GeneProduct ncbigene:610262
PYGB GeneProduct ncbigene:477003
UGP2 GeneProduct ncbigene:474615
GSK3A GeneProduct ncbigene:484476
PPP2R3A GeneProduct ncbigene:485672
GYG1 GeneProduct ncbigene:611614
PPP2R1A GeneProduct ncbigene:484335
CALM3 GeneProduct ncbigene:476428
PPP2R5E GeneProduct ncbigene:480349
PPP2CA GeneProduct ncbigene:403608
UGP2 GeneProduct ncbigene:474615
GYG2 GeneProduct ncbigene:491717
PPP2R5D GeneProduct ncbigene:481806
PPP2R2B GeneProduct ncbigene:478053
AGL GeneProduct ncbigene:479931
PPP2R5A GeneProduct ncbigene:490280
CALM2 GeneProduct ncbigene:474584
PPP2R3B GeneProduct ncbigene:607103
PHKA2 GeneProduct ncbigene:480857
PPP2R2A GeneProduct ncbigene:477374
GSK3B GeneProduct ncbigene:478575
PHKG1 GeneProduct ncbigene:489784
PPP2R1B GeneProduct ncbigene:479444
GBE1 GeneProduct ncbigene:478380
PGM1 GeneProduct ncbigene:479545
PPP2R4 GeneProduct ncbigene:491303
PYGL GeneProduct ncbigene:403738