GDP-L-galactose phosphorylase

GDP-L-galactose phosphorylase (EC 2.7.7.69, VTC2, VTC5) is an enzyme with systematic name GDP:alpha-L-galactose 1-phosphate guanylyltransferase.^[1]^[2]^[3]^[4] This enzyme catalyses the following chemical reaction

GDP-L-galactose + phosphate

\rightleftharpoons

alpha-L-galactose 1-phosphate + GDP

The enzyme catalyses a reaction of the Smirnoff-Wheeler pathway.

References

↑ Linster, C.L., Gomez, T.A., Christensen, K.C., Adler, L.N., Young, B.D., Brenner, C. and Clarke, S.G. (2007). "Arabidopsis VTC2 encodes a GDP-L-galactose phosphorylase, the last unknown enzyme in the Smirnoff-Wheeler pathway to ascorbic acid in plants". J. Biol. Chem. 282: 18879–18885. doi:10.1074/jbc.m702094200. PMID 17462988.
↑ Linster, C.L., Adler, L.N., Webb, K., Christensen, K.C., Brenner, C. and Clarke, S.G. (2008). "A second GDP-L-galactose phosphorylase in arabidopsis en route to vitamin C. Covalent intermediate and substrate requirements for the conserved reaction". J. Biol. Chem. 283: 18483–18492. doi:10.1074/jbc.m802594200. PMID 18463094.
↑ Dowdle, J., Ishikawa, T., Gatzek, S., Rolinski, S. and Smirnoff, N. (2007). "Two genes in Arabidopsis thaliana encoding GDP-L-galactose phosphorylase are required for ascorbate biosynthesis and seedling viability". Plant J. 52: 673–689. doi:10.1111/j.1365-313x.2007.03266.x. PMID 17877701.
↑ Muller-Moule, P. (2008). "An expression analysis of the ascorbate biosynthesis enzyme VTC2". Plant Mol. Biol. 68: 31–41. doi:10.1007/s11103-008-9350-4. PMID 18516687.

External links

GDP-L-galactose phosphorylase at the US National Library of Medicine Medical Subject Headings (MeSH)

Transferases: phosphorus-containing groups (EC 2.7)

2.7.1-2.7.4:
phosphotransferase/kinase
(PO₄)

2.7.1: OH acceptor	Hexo- Gluco- Fructo- Hepatic Galacto- Phosphofructo- 1 Liver Muscle Platelet 2 Riboflavin Shikimate Thymidine ADP-thymidine NAD⁺ Glycerol Pantothenate Mevalonate Pyruvate Deoxycytidine PFP Diacylglycerol Phosphoinositide 3 Class I PI 3 Class II PI 3 Sphingosine Glucose-1,6-bisphosphate synthase

2.7.2: COOH acceptor	Phosphoglycerate Aspartate kinase

2.7.3: N acceptor	Creatine

2.7.4: PO₄ acceptor	Phosphomevalonate Adenylate Nucleoside-diphosphate Uridylate Guanylate Thiamine-diphosphate

2.7.6: diphosphotransferase
(P₂O₇)

2.7.7: nucleotidyltransferase
(PO₄-nucleoside)

Polymerase

DNA polymerase	DNA-directed DNA polymerase I II III IV V RNA-directed DNA polymerase Reverse transcriptase Telomerase DNA nucleotidylexotransferase/Terminal deoxynucleotidyl transferase

RNA nucleotidyltransferase	RNA polymerase/DNA-directed RNA polymerase RNA polymerase I RNA polymerase II RNA polymerase III RNA polymerase IV Primase RNA-dependent RNA polymerase PNPase

Phosphorolytic
3' to 5' exoribonuclease

Nucleotidyltransferase

Guanylyltransferase

mRNA capping enzyme

Other

2.7.8: miscellaneous

Phosphatidyltransferases	CDP-diacylglycerol—glycerol-3-phosphate 3-phosphatidyltransferase CDP-diacylglycerol—serine O-phosphatidyltransferase CDP-diacylglycerol—inositol 3-phosphatidyltransferase CDP-diacylglycerol—choline O-phosphatidyltransferase

Glycosyl-1-phosphotransferase	N-acetylglucosamine-1-phosphate transferase

2.7.10-2.7.13: protein kinase
(PO₄; protein acceptor)

2.7.10: protein-tyrosine	see tyrosine kinases

2.7.11: protein-serine/threonine	see serine/threonine-specific protein kinases

2.7.12: protein-dual-specificity	see serine/threonine-specific protein kinases

2.7.13: protein-histidine	Protein-histidine pros-kinase Protein-histidine tele-kinase Histidine kinase

Enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases(list) EC2 Transferases(list) EC3 Hydrolases(list) EC4 Lyases(list) EC5 Isomerases(list) EC6 Ligases(list)

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