Glyceraldehyde 3-phosphate, also known as triose phosphate or 3-phosphoglyceraldehyde and abbreviated as G3P, GA3P, GADP, GAP, TP, GALP or PGAL, is a

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

that occurs as an intermediate in several central pathways of all organisms.Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. . With the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

H(O)CCH(OH)CH₂OPO₃^{^2-}, this anion is a monophosphate ester of

glyceraldehyde Glyceraldehyde (glyceral) is a triose monosaccharide with chemical formula C3 H6 O3. It is the simplest of all common aldoses. It is a sweet, colorless, crystalline solid that is an intermediate compound in carbohydrate metabolism. The word comes ...

An intermediate in both glycolysis and gluconeogenesis

Formation

D-glyceraldehyde 3-phosphate is formed from the following three compounds in reversible reactions: *Fructose-1,6-bisphosphate ( F1,6BP), catalyzed by

aldolase Fructose-bisphosphate aldolase (), often just aldolase, is an enzyme catalyzing a reversible reaction that splits the aldol, fructose 1,6-bisphosphate, into the triose phosphates dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phospha ...

. ''The numbering of the carbon atoms indicates the fate of the carbons according to their position in fructose 6-phosphate.'' *Dihydroxyacetone phosphate ( DHAP), catalyzed by

triose phosphate isomerase Triose-phosphate isomerase (TPI or TIM) is an enzyme () that catalyzes the reversible interconversion of the triose phosphate isomers dihydroxyacetone phosphate and D-glyceraldehyde 3-phosphate. TPI plays an important role in glycolysis and ...

. *1,3-bisphosphoglycerate ( 1,3BPG), catalyzed by

glyceraldehyde 3-phosphate dehydrogenase Glyceraldehyde 3-phosphate dehydrogenase (abbreviated GAPDH) () is an enzyme of about 37kDa that catalyzes the sixth step of glycolysis and thus serves to break down glucose for energy and carbon molecules. In addition to this long establishe ...

As a substrate

*To produce 1,3-bisphospho-D-glycerate in

glycolysis Glycolysis is the metabolic pathway that converts glucose () into pyruvate (). The free energy released in this process is used to form the high-energy molecules adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide (NADH ...

. D-glyceraldehyde 3-phosphate is also of some importance since this is how

glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...

(as DHAP) enters the glycolytic and gluconeogenic pathways. Furthermore, it is a participant in and a product of the

pentose phosphate pathway The pentose phosphate pathway (also called the phosphogluconate pathway and the hexose monophosphate shunt and the HMP Shunt) is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses (5-carbon sugars) as well as ribose 5-pho ...

Interactive pathway map

An intermediate in photosynthesis

During plant

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

, 2 equivalents of

glycerate 3-phosphate 3-Phosphoglyceric acid (3PG, 3-PGA, or PGA) is the conjugate acid of 3-phosphoglycerate or glycerate 3-phosphate (GP or G3P). This glycerate is a biochemically significant metabolic intermediate in both glycolysis and the Calvin-Benson cycle. Th ...

(GP; also known as 3-phosphoglycerate) are produced by the first step of the

light-independent reaction The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into ...

s when

ribulose 1,5-bisphosphate Ribulose 1,5-bisphosphate (RuBP) is an organic substance that is involved in photosynthesis, notably as the principal acceptor in plants. It is a colourless anion, a double phosphate ester of the ketopentose (ketone-containing sugar with five car ...

(RuBP) and

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

are catalysed by the

rubisco Ribulose-1,5-bisphosphate carboxylase-oxygenase, commonly known by the abbreviations RuBisCo, rubisco, RuBPCase, or RuBPco, is an enzyme () involved in the first major step of carbon fixation, a process by which atmospheric carbon dioxide is con ...

enzyme. The GP is converted to D-glyceraldehyde 3-phosphate (G3P) using the energy in ATP and the reducing power of

NADPH Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NAD ...

as part of the

Calvin cycle The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into ...

. This returns ADP, phosphate ions Pi, and

NADP Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NAD ...

+ to the

light-dependent reaction Light-dependent reactions is jargon for certain photochemical reactions that are involved in photosynthesis, the main process by which plants acquire energy. There are two light dependent reactions, the first occurs at photosystem II (PSII) and ...

s of photosynthesis for their continued function. RuBP is regenerated for the Calvin cycle to continue. G3P is generally considered the prime end-product of photosynthesis and it can be used as an immediate food nutrient, combined and rearranged to form monosaccharide sugars, such as

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...

, which can be transported to other cells, or packaged for storage as insoluble

polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...

s such as

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...

Balance sheet

6 CO₂ + 6 RuBP (+ energy from 12 ATP and 12 NADPH) →12 G3P (3-carbon) 10 G3P (+ energy from 6 ATP) → 6 RuBP (i.e. starting material regenerated) 2 G3P →

(6-carbon).

In tryptophan biosynthesis

Glyceraldehyde 3-phosphate occurs as a byproduct in the biosynthesis pathway of

tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α- carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...

, an essential

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

that cannot be produced by the human body.

In thiamine biosynthesis

Glyceraldehyde 3-phosphate occurs as a reactant in the biosynthesis pathway of

thiamine Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thi ...

(Vitamin B₁), another substance that cannot be produced by the human body.

References

External links

D-Glyceraldehyde 3-phosphate and the reactions and pathways it participates in
from the KEGG PATHWAY Database
Glyceraldehyde 3-phosphate and the reactions and pathways it participates in
from the KEGG PATHWAY Database {{Fructose and galactose metabolic intermediates Photosynthesis Organophosphates Phosphate esters Glycolysis