Glycogen metabolism (WP160)

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 [http://en.wikipedia.org/wiki/Glycogen Wikipedia].
last edited

Authors

Kdahlquist, MaintBot, M.Ramirez, AlexanderPico, Christine Chichester, Mkutmon, and Eweitz

Cited In

Organism

Rattus norvegicus

Communities

Annotations

Pathway Ontology: glycogen metabolic pathway

Participants

Label Type Compact Identifier
Pygm GeneProduct ncbigene:24701
Ppp2cb GeneProduct ncbigene:24673
Phkb GeneProduct ncbigene:361377
Gys2 GeneProduct ncbigene:25623
Ppp2r5b GeneProduct ncbigene:309179
Phkg2 GeneProduct ncbigene:140671
Glycogen Metabolite None
Ppp2r5c GeneProduct ncbigene:691318
CALM1 GeneProduct ncbigene:24242
cAMP Metabolite hmdb:HMDB0000058
Phka1 GeneProduct ncbigene:64561
Ppp2r2c GeneProduct ncbigene:117256
Pygb GeneProduct ncbigene:25739
Ugp2 GeneProduct ncbigene:289827
Glycogen (n+1) Metabolite None
Glucose-1-phosphate Metabolite None
Gys1 GeneProduct ncbigene:690987
Gsk3a GeneProduct ncbigene:50686
Ppp2r3a GeneProduct ncbigene:363122
Gyg1 GeneProduct ncbigene:81675
Ppp2r1a GeneProduct ncbigene:117281
CALM3 GeneProduct ncbigene:24244
Ppp2r5e GeneProduct ncbigene:299147
Ppp2ca GeneProduct ncbigene:24672
Ugp2 GeneProduct ncbigene:289827
UDP-glucose Metabolite hmdb:HMDB0000286
GYG2 GeneProduct None
Ppp2r5d GeneProduct ncbigene:363193
Ppp2r2b GeneProduct ncbigene:60660
Glucose 1-phosphate Metabolite hmdb:HMDB0001586
Glycogen Metabolite None
Glucose Metabolite None
Agl GeneProduct ncbigene:362029
Ppp2r5a GeneProduct ncbigene:312754
CALM2 GeneProduct ncbigene:50663
PPP2R3B GeneProduct None
Phka2 GeneProduct ncbigene:678739
Ppp2r2a GeneProduct ncbigene:117104
Glycogen (n+1) Metabolite None
Gsk3b GeneProduct ncbigene:84027
Phkg1 GeneProduct ncbigene:29353
Ppp2r1b GeneProduct ncbigene:315648
Gbe1 GeneProduct ncbigene:288333
Pgm1 GeneProduct ncbigene:24645
Glucose-6-phosphate Metabolite None
Ppp2r4 GeneProduct ncbigene:362102
Pygl GeneProduct ncbigene:64035

References