同: G-6-P
同: G6P
同: G6P

WordNet

a salt of phosphoric acid (同)orthophosphate, inorganic_phosphate
carbonated drink with fruit syrup and a little phosphoric acid
a monosaccharide sugar that has several forms; an important source of physiological energy

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〈U〉リン酸塩 / 《複数形で》リン酸肥料
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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/05/14 21:32:49」(JST)

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Glucose 6-phosphate (also known as Robison ester) is glucose sugar phosphorylated on carbon 6. This compound is very common in cells as the vast majority of glucose entering a cell will become phosphorylated in this way.

Because of its prominent position in cellular chemistry, glucose 6-phosphate has many possible fates within the cell. It lies at the start of two major metabolic pathways, Glycolysis and Pentose phosphate pathway. In addition to these metabolic pathways, glucose 6-phosphate may also be converted to glycogen or starch for storage. This storage is in the liver and muscles in the form of glycogen for most multicellular animals, and in intracellular starch or glycogen granules for most other organisms.

Production of glucose 6-phosphate

From glucose

Within a cell, glucose 6-phosphate is produced by phosphorylation of glucose on the sixth carbon. This is catalyzed by the enzyme hexokinase in most cells, and, in higher animals, glucokinase in certain cells, most notably liver cells. One molecule of ATP is consumed in this reaction.

D-Glucose	Hexokinase		α-D-Glucose 6-phosphate

	ATP	ADP

	PO3- 4	H₂O

	Glucose 6-phosphatase

Compound C00031 at KEGG Pathway Database. Enzyme 2.7.1.1 at KEGG Pathway Database. Compound C00668 at KEGG Pathway Database. Reaction R01786 at KEGG Pathway Database.

The major reason for the immediate phosphorylation of glucose is to prevent diffusion out of the cell. The phosphorylation adds a charged phosphate group so the glucose 6-phosphate cannot easily cross the cell membrane.

From glycogen

Glucose-6-phosphate is also produced during glycogenolysis from glucose-1-phosphate, the first product of the breakdown of glycogen polymers.

Pentose phosphate pathway

When the ratio of NADP⁺ : NADPH increases, the body realizes it needs to produce more NADPH (a reducing agent for several reactions like fatty acid synthesis and glutathione reduction in erythrocytes). This will cause the G6P to be dehydrogenated by glucose 6-phosphate dehydrogenase. This reversible reaction is the initial step of the pentose phosphate pathway, which generates the useful cofactor NADPH as well as ribulose-5-phosphate, a carbon source for the synthesis of other molecules. Also, if the body needs nucleotide precursors of DNA for growth and synthesis, G6P will also be dehydrogenated and enter the pentose phosphate pathway.

Glycolysis

If the cell needs energy or carbon skeletons for synthesis then glucose 6-phosphate is targeted for glycolysis. Glucose 6-phosphate is first isomerized to fructose 6-phosphate by phosphoglucose isomerase.

α-D-Glucose 6-phosphate	Phosphoglucose isomerase	β-D-Fructose 6-phosphate





	Phosphoglucose isomerase

Compound C00668 at KEGG Pathway Database. Enzyme 5.3.1.9 at KEGG Pathway Database. Compound C05345 at KEGG Pathway Database. Reaction R00771 at KEGG Pathway Database.

This reaction converts glucose 6-phosphate to fructose 6-phosphate in preparation for phosphorylation to Fructose-1,6-bisphosphate. The addition of the 2nd phosphoryl group to produce Fructose-1,6-bisphosphate is an irreversible step, and so is used to irreversibly target the glucose 6-phosphate breakdown to provide energy for ATP production via glycolysis.

Click on genes, proteins and metabolites below to link to respective articles. ^{[§ 1]}

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Glycolysis and Gluconeogenesis edit

^ The interactive pathway map can be edited at WikiPathways: "GlycolysisGluconeogenesis_WP534".

Storage as glycogen

If blood glucose levels are high, the body needs a way to store the excess glucose. After being converted to G6P, the molecule can be turned into glucose-1-phosphate by phosphoglucomutase. Glucose-1-phosphate can then be combined withn uridine triphosphate (UTP) to form UDP-glucose, driven by the hydrolysis of UTP, releasing phosphate. Now, the activated UDP-glucose can add to a growing glycogen molecule with the help of glycogen synthase. This is a very efficient storage mechanism for glucose since it costs the body only 1 ATP to store the 1 glucose molecule and virtually no energy to remove it from storage. It is important to note that glucose-6-phosphate is an allosteric activator of glycogen synthase, which makes sense because when the level of glucose is high the body should store the excess glucose as glycogen. On the other hand, glycogen synthase is inhibited when it is phosphorylated by protein kinase during times of high stress or low levels of blood glucose, via hormone induction by glucagon or adrenaline.

When the body needs glucose for energy, glycogen phosphorylase, with the help of an orthophosphate, can cleave away a molecule from the glycogen chain. The cleaved molecule is in the form of glucose-1-phosphate, which can be converted into G6P by phosphoglucomutase. Next, the phosphoryl group on G6P can be cleaved by glucose-6-phosphatase so that a free glucose can be formed. This free glucose can pass through membranes and can enter the bloodstream to travel to other places in the body.

Dephosphorylation and release into bloodstream

Liver cells possess glucose-6-phosphatase, which removes the phosphate group from glucose-6-phosphate produced during glycogenolysis or gluconeogenesis. Free glucose is sent into the bloodstream for uptake by other cells. Muscle cells lack this enzyme, so myofibers use glucose-6-phosphate in their own metabolic pathways.

References

Berg, Jeremy M.; Tymoczko, Stryer (2002). Biochemistry (5th ed.). New York: W.H. Freeman and Company. ISBN 0-7167-3051-0.

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. グルコース-6-リン酸脱水素酵素欠損症の診断および治療 diagnosis and treatment of glucose 6 phosphate dehydrogenase deficiency
2. グルコース-6-リン酸脱水素酵素欠損症の臨床症状 clinical manifestations of glucose 6 phosphate dehydrogenase deficiency
3. グルコース-6-リン酸脱水素酵素欠損症の遺伝学および病態生理 genetics and pathophysiology of glucose 6 phosphate dehydrogenase deficiency
4. 低リン血症の原因 causes of hypophosphatemia
5. 低リン血症の診断および治療 diagnosis and treatment of hypophosphatemia

English Journal

Drosophila melanogaster larvae fed by glucose and fructose demonstrate difference in oxidative stress markers and antioxidant enzymes of adult flies.

Lushchak OV, Rovenko BM, Gospodaryov DV, Lushchak VI.AbstractActivities of antioxidant and associated enzymes, and oxidative stress markers were assessed in newly enclosed adult fruit flies Drosophila melanogaster developed on diets with 4 and 10% glucose or fructose. In fly males, 10% fructose promoted higher content of protein carbonyls and catalase activity, but lower superoxide dismutase (SOD) activity than 4%, while in females-lower levels of high molecular mass thiols (H-SH). Females at all diets had virtually the same level of lipid peroxides, low-molecular-mass thiols, catalase, and superoxide dismutase activities. Fed with 4% fructose and glucose males demonstrated 24 and 26% lower H-SH level than females, respectively. On diets with 4% glucose, 10% glucose and fructose females had 32, 26 and 27% lower catalase activity than respective males, and 1.3-1.5-fold lower glucose-6-phosphate dehydrogenase activity on glucose-containing diets. Strong positive correlations between H-SH level and G6PD activity, as well as between catalase and G6PDH activity were found. These results suggest that type and concentration of dietary carbohydrate affect antioxidant defense in fruit flies. It also substantially depends on fly sex, comprising presumably levels of protein carbonyls and lipid peroxides, as well as catalase and SOD activities in males and G6PDH activity in females.
Comparative biochemistry and physiology. Part A, Molecular & integrative physiology.Comp Biochem Physiol A Mol Integr Physiol.2011 Sep;160(1):27-34. Epub 2011 May 15.
Activities of antioxidant and associated enzymes, and oxidative stress markers were assessed in newly enclosed adult fruit flies Drosophila melanogaster developed on diets with 4 and 10% glucose or fructose. In fly males, 10% fructose promoted higher content of protein carbonyls and catalase activit
PMID 21609775

Influence of tamoxifen on gluconeogenesis and glycolysis in the perfused rat liver.

Marek CB, Peralta RM, Itinose AM, Bracht A.SourceLaboratory of Toxicology, State University of Western Parana, Cascavel, Brazil.
Chemico-biological interactions.Chem Biol Interact.2011 Aug 15;193(1):22-33. Epub 2011 May 4.
The actions of tamoxifen, a selective estrogen receptor modulator used in chemotherapy and chemo-prevention of breast cancer, on glycolysis and gluconeogenesis were investigated in the isolated perfused rat liver. Tamoxifen inhibited gluconeogenesis from both lactate and fructose at very low concent
PMID 21570382

Japanese Journal

Wheat Bran Protects Fischer-344 Rats from Diquat-Induced Oxidative Stress by Activating Antioxidant System: Selenium as an Antioxidant

HIGUCHI Masashi,OSHIDA Junichi,ORINO Koichi,WATANABE Kiyotaka
Bioscience, Biotechnology, and Biochemistry 75(3), 496-499, 2011
… Although feeding wheat bran did not affect the concentration of hepatic non-protein sulfhydryl or the activity of glucose 6-phosphate dehydrogenase in the saline-injected rats, these values were significantly higher in the rats fed PD containing wheat bran (W-PD) than in rats fed only PD after administering diquat. …
NAID 130000645252

Incidence and mutation analysis of glucose-6-phosphate dehydrogenase deficiency in eastern indonesian populations

Tantular Indah S.,Matsuoka Hiroyuki,Kasahara Yuichi,Pusarawati Suhintam,Kanbe Toshio,Tuda Josef S. B.,Kido Yasutoshi,Dachlan Yoes P.,Kawamoto Fumihiko
Acta Medica Okayama 64(6), 367-373, 2010-12
… We conducted a field survey of glucose-6-phosphate dehydrogenese (G6PD) deficiency in the eastern Indonesian islands, and analyzed G6PD variants molecularly. … The incidence of G6PD deficiency in 5 ethnic groups (Manggarai, Bajawa, Nage-Keo, Larantuka, and Palue) on the Flores and Palue Islands was lower than that of another native group, Sikka, or a nonnative group, Riung. …
NAID 120002690099

Related Pictures

★リンクテーブル★

リンク元	「グルコース6-リン酸」「グルコキナーゼ」「クレアチンキナーゼ」「グルコース-6-ホスファターゼ」「フルクトース6-リン酸」
拡張検索	「glucose-6-phosphate isomerase」「glucose-6-phosphate dehydrogenase deficiency」「glucose-6-phosphate translocase」「glucose-6-phosphate dehydrogenase」
関連記事	「phosphate」

「グルコース6-リン酸」

Glucose 6-phosphate
	IUPAC name D-Glucopyranose 6-phosphate
Identifiers
CAS number	56-73-5
PubChem	208
ChemSpider	17216117
MeSH	Glucose-6-phosphate
ChEBI	CHEBI:4170
Jmol-3D images	Image 1
	SMILES O[C@H]1[C@H](O)[C@@H](COP(O)(O)=O)OC(O)[C@@H]1O ;
	InChI InChI=1S/C6H11O9P/c7-3-2(1-14-16(11,12)13)15-6(10)5(9)4(3)8/h2-10H,1H2,(H2,11,12,13)/t2-,3-,4+,5-,6?/m1/s1 ; Key: NBSCHQHZLSJFNQ-GASJEMHNSA-N InChI=1/C6H11O9P/c7-3-2(1-14-16(11,12)13)15-6(10)5(9)4(3)8/h2-10H,1H2,(H2,11,12,13)/t2-,3-,4+,5-,6u/m1/s1; Key: NBSCHQHZLSJFNQ-SEZHTIIRBF ;
Properties
Molecular formula	C6H13O9P
Molar mass	260.136
	Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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	Infobox references