Glycogen and its metabolism: some new developments and old themes

• Published in: Biochemical journal Vol. 441; no. 3; p. 763
• Main Authors: Roach, Peter J, Depaoli-Roach, Anna A, Hurley, Thomas D, Tagliabracci, Vincent S
• Format: Journal Article
• Language: English
• Published: England 01.02.2012
• Subjects: Amino Acid Sequence; Animals; Biology - trends; Carbohydrate Metabolism - genetics; Carbohydrate Metabolism - physiology; Concept Formation; Gluconeogenesis - physiology; Glycogen - chemistry; Glycogen - metabolism; Glycogen - physiology; Glycogenolysis - physiology; Humans; Metabolic Networks and Pathways - genetics; Metabolic Networks and Pathways - physiology; Mice; Models, Biological; Models, Molecular; Molecular Sequence Data; Sequence Homology, Amino Acid
• ISSN: 1470-8728
• DOI: 10.1042/BJ20111416

Glycogen is a branched polymer of glucose that acts as a store of energy in times of nutritional sufficiency for utilization in times of need. Its metabolism has been the subject of extensive investigation and much is known about its regulation by hormones such as insulin, glucagon and adrenaline (epinephrine). There has been debate over the relative importance of allosteric compared with covalent control of the key biosynthetic enzyme, glycogen synthase, as well as the relative importance of glucose entry into cells compared with glycogen synthase regulation in determining glycogen accumulation. Significant new developments in eukaryotic glycogen metabolism over the last decade or so include: (i) three-dimensional structures of the biosynthetic enzymes glycogenin and glycogen synthase, with associated implications for mechanism and control; (ii) analyses of several genetically engineered mice with altered glycogen metabolism that shed light on the mechanism of control; (iii) greater appreciation of the spatial aspects of glycogen metabolism, including more focus on the lysosomal degradation of glycogen; and (iv) glycogen phosphorylation and advances in the study of Lafora disease, which is emerging as a glycogen storage disease.