Glycogenin
| Glycogenin | ||
|---|---|---|
| Mass / length primary structure | 349 amino acids | |
| Secondary to quaternary structure | Homodimer | |
| Cofactor | manganese | |
| Isoforms | GN-1L, GN-1, GN-1S, GN-2α, GN-2β, GN-2γ, GN-2δ, GN-2ε, GN-2ζ | |
| Identifier | ||
| Gene name (s) | GYG1 , GYG2 | |
| External IDs | ||
| Enzyme classification | ||
| EC, category | 2.4.1.186 , glycosyl transferase | |
| Response type | Transfer of a glucose residue | |
| Substrate | Glucosyl n -Glycogenin + UDP-glucose (n = 0-12) | |
| Products | Glucosyl n + 1 -Glycogenin + UDP | |
| Occurrence | ||
| Homology family | Glycogenin | |
| Parent taxon | Mushrooms / multicellular cells | |
Glycogenins are enzymes that attach glucose residues to themselves - the polysaccharide chain can be up to 13 glucose units long. This reaction is necessary to get the production of long-chain polysaccharides , especially glycogen , going, because the enzyme glycogen synthase can only work if short chains are already present. Glycogenins are found in mushrooms and multicellular organisms . Humans have two homologous genes , each of which allows for multiple isoforms of the enzyme located in different tissue types. Glycogenin is tightly bound to glycogen synthase , so it can be called its cofactor . Mutations in the GYG1 gene are responsible for an inherited glycogen storage disease .
Catalyzed reactions
Glycogenin + +
Glycogenin catalyzes the addition of glucose to itself by binding the first UDP-glucose , formed from UTP and glucose-1-phosphate, to the Tyr-194 residue of its active site. This creates UDP .
+ +
glycogenin.svg)
The enzyme then lines up further glucose residues up to a certain limit (approx. 5-13), after which the glycogen synthase takes over the further polymerization. The glycogenin remains bound to the glycogen chain. After possible breakdown of the chain, the enzyme is available as a germ cell for renewed glycogen synthesis. H. it is not dismantled.
See also
Individual evidence
- ↑ UniProt P46976 , UniProt O15488
- ↑ Skurat AV, Dietrich AD, Roach PJ: Interaction between glycogenin and glycogen synthase . In: Arch. Biochem. Biophys. . 456, No. 1, December 2006, pp. 93-7. doi : 10.1016 / j.abb.2006.09.024 . PMID 17055998 . PMC 1769445 (free full text).
- ↑ Hurley TD, Walls C, Bennett JR, Roach PJ, Wang M: Direct detection of glycogenin reaction products during glycogen initiation . In: Biochem. Biophys. Res. Commun. . 348, No. 2, September 2006, pp. 374-8. doi : 10.1016 / j.bbrc.2006.07.106 . PMID 16889748 . PMC 1635985 (free full text).
- ↑ Wilson RJ, Gusba JE, Robinson DL, Graham TE: Glycogenin protein and mRNA expression in response to changing glycogen concentration in exercise and recovery . In: Am. J. Physiol. Endocrinol. Metab. . 292, No. 6, June 2007, pp. E1815-22. doi : 10.1152 / ajpendo.00598.2006 . PMID 17311895 .
