Glycogen metabolism (WP955)

Pan troglodytes

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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Pan troglodytes



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:451299
PPP2CB GeneProduct ncbigene:464100
PHKB GeneProduct ncbigene:465150
GYS2 GeneProduct ncbigene:465336
PHKG2 GeneProduct ncbigene:741602
PPP2R5C GeneProduct ncbigene:453170
CALM1 GeneProduct ncbigene:738819
PHKA1 GeneProduct ncbigene:465713
PPP2R2C GeneProduct ncbigene:461101
PYGB GeneProduct ncbigene:469908
UGP2 GeneProduct ncbigene:459273
GYS1 GeneProduct ncbigene:456196
GSK3A GeneProduct ncbigene:456071
PPP2R3A GeneProduct ncbigene:460715
GYG1 GeneProduct ncbigene:460765
PPP2R1A GeneProduct ncbigene:468983
CALM3 GeneProduct ncbigene:456153
PPP2R5E GeneProduct ncbigene:452962
PPP2CA GeneProduct ncbigene:471633
UGP2 GeneProduct ncbigene:459273
GYG2 GeneProduct ncbigene:465469
PPP2R5D GeneProduct ncbigene:462705
PPP2R2B GeneProduct ncbigene:462170
AGL GeneProduct ncbigene:469392
PPP2R5A GeneProduct ncbigene:457716
CALM2 GeneProduct ncbigene:459213
PHKA2 GeneProduct ncbigene:465523
PPP2R2A GeneProduct ncbigene:464068
GSK3B GeneProduct ncbigene:470896
PHKG1 GeneProduct ncbigene:746486
PPP2R1B GeneProduct ncbigene:466778
GBE1 GeneProduct ncbigene:460520
PGM1 GeneProduct ncbigene:456908
PPP2R4 GeneProduct ncbigene:464784
PYGL GeneProduct ncbigene:742309