''sn''-Glycerol 3-phosphate is the organic ion with the formula HOCH₂CH(OH)CH₂OPO₃^2-. It is one of three

stereoisomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in ...

s of the ester of dibasic phosphoric acid (HOPO₃^2-) and

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 ...

. It is a component of

glycerophospholipid Glycerophospholipids or phosphoglycerides are glycerol-based phospholipids. They are the main component of biological membranes. Two major classes are known: those for bacteria and eukaryotes and a separate family for archaea. Structures The t ...

s. Equally appropriate names in biochemical context include glycerol-3-phosphate, 3-''O''-phosphonoglycerol, 3-phosphoglycerol; and Gro3P. From a historical reason, it is also known as -glycerol 3-phosphate, -glycerol 1-phosphate, -α-glycerophosphoric acid.

Biosynthesis

Glycerol 3-phosphate is synthesized by reducing

dihydroxyacetone phosphate Dihydroxyacetone phosphate (DHAP, also glycerone phosphate in older texts) is the anion with the formula HOCH2C(O)CH2OPO32-. This anion is involved in many metabolic pathways, including the Calvin cycle in plants and glycolysis.Nelson, D. L.; ...

(DHAP), an intermediate 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 ...

. The reduction is catalyzed by

glycerol-3-phosphate dehydrogenase ''sn''-Glycerol 3-phosphate is the organic ion with the formula HOCH2CH(OH)CH2OPO32-. It is one of three stereoisomers of the ester of dibasic phosphoric acid (HOPO32-) and glycerol. It is a component of glycerophospholipids. Equally appropriat ...

. DHAP and thus glycerol 3-phosphate can also be synthesized from

amino acids 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 ...

and

citric acid cycle The citric acid cycle (CAC)—also known as the Krebs cycle or the TCA cycle (tricarboxylic acid cycle)—is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins ...

intermediates via the

glyceroneogenesis Glyceroneogenesis is a metabolic pathway which synthesizes glycerol 3-phosphate or triglyceride from precursors other than glucose. Usually glycerol 3-phosphate is generated from glucose by glycolysis, but when glucose concentration drops in the cyt ...

pathway. : Dihydroxyacetonphosphat Skelett

+ NAD(P)H + H⁺ → Glycerin-3-phosphat Skelett

+ NAD(P)⁺ It is also synthesized by the

phosphorylation In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, wh ...

, which is generated by hydrolysis of

fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers spec ...

s. This esterification is catalyzed by

glycerol kinase Glycerol kinase, encoded by the gene ''GK'', is a phosphotransferase enzyme involved in triglycerides and glycerophospholipids synthesis. Glycerol kinase catalyzes the transfer of a phosphate from ATP to glycerol thus forming glycerol 3-phosph ...

. :

+ ATP →

+ ADP

Metabolism and biological function

Glycerol 3-phosphate is a starting material for ''de novo'' synthesis of

glycerolipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins Vitamin A, A, Vitamin D, D, Vitamin E, E and Vitamin K, K), monoglycerides, diglycerides, phospholipids, and o ...

s. In

eukaryotes Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

, it is first acylated on its ''sn''-1 position by an ER- or mitochondrial membrane enzyme,

glycerol-3-phosphate O-acyltransferase In enzymology, a glycerol-3-phosphate O-acyltransferase () is an enzyme that catalyzes the chemical reaction :acyl-CoA + sn-glycerol 3-phosphate \rightleftharpoons CoA + 1-acyl-sn-glycerol 3-phosphate Thus, the two substrates of this enzyme are ...

. A second acyl group is subsequently installed on the ''sn''-2 position making

phosphatidic acid Phosphatidic acids are anionic phospholipids important to cell signaling and direct activation of lipid-gated ion channels. Hydrolysis of phosphatidic acid gives rise to one molecule each of glycerol and phosphoric acid and two molecules of fatty ac ...

s. :

Acyl-CoA Acyl-CoA is a group of coenzymes that metabolize fatty acids. Acyl-CoA's are susceptible to beta oxidation, forming, ultimately, acetyl-CoA. The acetyl-CoA enters the citric acid cycle, eventually forming several equivalents of ATP. In this way ...

→

Lysophosphatidic acid Lysophosphatidic acid (LPA) is a phospholipid derivative that can act as a signaling molecule. Function LPA acts as a potent mitogen due to its activation of three high-affinity G-protein-coupled receptors called LPAR1, LPAR2, and LPAR3 (also kn ...

+ CoA

Glycerol-1-phosphatase The enzyme glycerol-1-phosphatase (EC 3.1.3.21) catalyzes the reaction :glycerol 1-phosphate + H2O \rightleftharpoons glycerol + phosphate This enzyme belongs to the family of hydrolases, specifically those acting on phosphoric monoester bonds. ...

catalyzes the hydrolysis of glycerol 3-phosphate to regenerate

, allowing glycerol fermentation to produce glycerol from

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 ...

through glycolysis pathway. A number of organisms express this enzyme. : Glycerin-3-phosphat Skelett

+ H₂O →

+ Pi

Shuttle system

Glycerol-3-phosphate dehydrogenases are located both in the

cytosol The cytosol, also known as cytoplasmic matrix or groundplasm, is one of the liquids found inside cells (intracellular fluid (ICF)). It is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondri ...

and the intermembrane face of

mitochondrial inner membrane The inner mitochondrial membrane (IMM) is the mitochondrial membrane which separates the mitochondrial matrix from the intermembrane space. Structure The structure of the inner mitochondrial membrane is extensively folded and compartmentalized. ...

. Glycerol 3-phosphate (G3P) and

(DHAP) are molecules so small that they can permeate the mitochondrial outer membrane through porins and shuttle between two dehydrogenases. Using this shuttle system,

NADH Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an aden ...

generated by cytosolic metabolisms including glycolysis is reoxidized to NAD⁺ reducing DHAP to G3P, and the reducing equivalent can be used for generating a

proton gradient An electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can move across a membrane. The gradient consists of two parts, the chemical gradient, or difference in solute concentration across a membrane, and th ...

across the mitochondrial inner membrane by coupling and oxidizing G3P and reducing

quinone The quinones are a class of organic compounds that are formally "derived from aromatic compounds

uch as benzene or naphthalene Uch ( pa, ; ur, ), frequently referred to as Uch Sharīf ( pa, ; ur, ; ''"Noble Uch"''), is a historic city in the southern part of Pakistan's Punjab province. Uch may have been founded as Alexandria on the Indus, a town founded by Alexand ...

by conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of double ...

. The Glycerol 3-phosphate shuttle is an emergency back-up system to supply

neurons A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...

' demand of energy.

Dephosphorylation

Glycerol-3-phosphate was found to be a substrate for the enzyme

phosphoglycolate phosphatase Phosphoglycolate phosphatase(EC 3.1.3.18; systematic name 2-phosphoglycolate phosphohydrolase), also commonly referred to as phosphoglycolate hydrolase, 2-phosphoglycolate phosphatase, P-glycolate phosphatase, and phosphoglycollate phosphatase, is ...

(PGP, or G3PP) in mammals in 2015. G3PP activity has subsequently been suggested to have a regulatory role in central metabolism and stress response.

Glycerol 1-phosphate

Glycerol 1-phosphate ''sn''-Glycerol 1-phosphate is the conjugate base of a phosphoric ester of glycerol. It is a component of ether lipids, which are common for archaea. Biosynthesis and metabolism Glycerol 1-phosphate is synthesized by reducing dihydroxyacetone ...

, sometimes called as -glycerol 3-phosphate, is the

enantiomer In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...

of glycerol 3-phosphate. Most higher organisms use the 3-phosphate, or -configuration, for glycerolipid backbone. The 1-phosphate is specifically found in archeal lipids.

Notes

{{DEFAULTSORT:Glycerol 3-Phosphate Vicinal diols Organophosphates Glycerol esters Phosphate esters