Reactome: A Curated Pathway Database

Glycogen synthesis (R-HSA-3322077)

Species Homo sapiens


Glycogen, a highly branched glucose polymer, is formed and broken down in most human tissues, but is most abundant in liver and muscle, where it serves as a major stored fuel. Glycogen metabolism has been studied in most detail in muscle, although considerable experimental data are available concerning these reactions in liver as well. Glycogen metabolism in other tissues has not been studied as extensively, and is thought to resemble the muscle process. Glycogen synthesis involves five reactions. The first two, conversion of glucose 6-phosphate to glucose 1-phosphate and synthesis of UDP-glucose from glucose 1-phosphate and UTP, are shared with several other pathways. The next three reactions, the auto-catalyzed synthesis of a glucose oligomer on glycogenin, the linear extension of the glucose oligomer catalyzed by glycogen synthase, and the formation of branches catalyzed by glycogen branching enzyme, are unique to glycogen synthesis. Repetition of the last two reactions generates large, extensively branched glycogen polymers. The catalysis of glycogenin glucosylation and oligoglucose chain extension by distinct isozymes in liver and nonhepatic tissues allows them to be regulated independently (Agius 2008; Bollen et al. 1998; Roach et al. 2012).

Locations in the PathwayBrowser
Additional Information
GO Biological Process glycogen biosynthetic process (0005978)
Literature References
pubMedId Title Journal Year
18651836 Glucokinase and molecular aspects of liver glycogen metabolism Biochem. J. 2008
9806880 Specific features of glycogen metabolism in the liver Biochem. J. 1998
22248338 Glycogen and its metabolism: some new developments and old themes Biochem. J. 2012