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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/04/28 06:19:09」(JST)

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Chemical structure of the diglyceride 1-palmitoyl-2-oleoyl-glycerol

A di-glyceride, or a diacyl-glycerol (DAG), is a glyceride consisting of two fatty acid chains covalently bonded to a glycerol molecule through ester linkages. One example, shown on the right, is 1-palmitoyl-2-oleoyl-glycerol, which contains side-chains derived from palmitic acid and oleic acid. Diacylglycerols can also have many different combinations of fatty acids attached at both the C-1 and C-2 positions.

Food additive

Mono- and diglycerides (E471) are common food additives used to blend together certain ingredients, such as oil and water, which would not otherwise blend well. The values given in the nutritional labels for total fat, saturated fat, and trans fat do not include those present in mono- and diglycerides^{[citation needed]}.

The commercial source may be either animal (cow- or hog-derived) or vegetable, derived primarily from partially hydrogenated soy bean and canola oil.^{[citation needed]} They may also be synthetically produced. They are often found in bakery products, beverages, ice cream, peanut butter, chewing gum, shortening, whipped toppings, margarine, confections, and candies.

Biological functions

Protein kinase C activation

PIP2 cleavage to IP3 and DAG initiates intracellular calcium release and PKC activation.

In biochemical signaling, diacylglycerol functions as a second messenger signaling lipid, and is a product of the hydrolysis of the phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) by the enzyme phospholipase C (PLC) (a membrane-bound enzyme) that, through the same reaction, produces inositol trisphosphate (IP₃). Although inositol trisphosphate diffuses into the cytosol, diacylglycerol remains within the plasma membrane, due to its hydrophobic properties. IP₃ stimulates the release of calcium ions from the smooth endoplasmic reticulum, whereas DAG is a physiological activator of protein kinase C (PKC). The production of DAG in the membrane facilitates translocation of PKC from the cytosol to the plasma membrane.

Diacylglycerol can be mimicked by the tumor-promoting compounds phorbol esters.^[1]

Other

In addition to activating PKC, diacylglycerol has a number of other functions in the cell:

a source for prostaglandins
a precursor of the endocannabinoid 2-arachidonoylglycerol
an activator of a subfamily of transient receptor potential canonical (TRPC) cation channels, TRPC3/6/7.

Metabolism

glycerol-3-phosphate

Synthesis of diacylglycerol begins with glycerol-3-phosphate, which is derived primarily from dihydroxyacetone phosphate, a product of glycolysis (usually in the cytoplasm of liver or adipose tissue cells). Glycerol-3-phosphate is first acylated with acyl-coenzyme A (acyl-CoA) to form lysophosphatidic acid, which is then acylated with another molecule of acyl-CoA to yield phosphatidic acid. Phosphatidic acid is then de-phosphorylated to form diacylglycerol.

Diacylglycerol is a precursor to triacylglycerol (triglyceride), which is formed in the addition of a third fatty acid to the diacylglycerol under the catalysis of diglyceride acyltransferase.

Since diacylglycerol is synthesized via phosphatidic acid, it will usually contain a saturated fatty acid at the C-1 position on the glycerol moiety and an unsaturated fatty acid at the C-2 position.^[2]

Diacylglycerol can be phosphorylated to phosphatidic acid by diacylglycerol kinase.

References

^ Blumberg, Peter M. (1988). "Protein Kinase C as the Receptor for the Phorbol Ester Tumor Promoters: Sixth Rhoads Memorial Award Lecture". Cancer Research 48 (1): 1–8. PMID 3275491.
^ Berg J, Tymoczko JL, Stryer L (2006). Biochemistry (6th ed.). San Francisco: W. H. Freeman. ISBN 0-7167-8724-5. ^{[page needed]}

UpToDate Contents

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English Journal

Correlative and integrated light and electron microscopy of in-resin GFP fluorescence, used to localise diacylglycerol in mammalian cells.

Peddie CJ1, Blight K1, Wilson E1, Melia C2, Marrison J3, Carzaniga R1, Domart MC4, O׳Toole P3, Larijani B5, Collinson LM1.
Ultramicroscopy.Ultramicroscopy.2014 Aug;143C:3-14. doi: 10.1016/j.ultramic.2014.02.001. Epub 2014 Feb 22.
Fluorescence microscopy of GFP-tagged proteins is a fundamental tool in cell biology, but without seeing the structure of the surrounding cellular space, functional information can be lost. Here we present a protocol that preserves GFP and mCherry fluorescence in mammalian cells embedded in resin wi
PMID 24637200

Simultaneous production of fatty acid methyl esters and diglycerides by four recombinant Candida rugosa lipase's isozymes.

Chang SW1, Huang M2, Hsieh YH3, Luo YT4, Wu TT5, Tsai CW6, Chen CS2, Shaw JF7.
Food chemistry.Food Chem.2014 Jul 15;155:140-5. doi: 10.1016/j.foodchem.2014.01.035. Epub 2014 Jan 23.
In this study, the catalytic efficiency of four recombinant CRL (Candida rugosa lipase) isozymes (LIP1-LIP4) towards the production of fatty acid methyl ester (FAME) was compared and evaluated as an alternative green method for industrial applications. The results indicated that the recombinant C. r
PMID 24594166

The C1B domains of novel PKCε and PKCη have a higher membrane binding affinity than those of the also novel PKCδ and PKCθ.

Egea-Jiménez AL1, Corbalán-García S1, Gómez-Fernández JC2.
Biochimica et biophysica acta.Biochim Biophys Acta.2014 Jul;1838(7):1898-909. doi: 10.1016/j.bbamem.2014.04.003. Epub 2014 Apr 13.
The C1 domains of novel PKCs mediate the diacylglycerol-dependent translocation of these enzymes. The four different C1B domains of novel PKCs (δ, ε, θ and η) were studied, together with different lipid mixtures containing acidic phospholipids and diacylglycerol or phorbol ester. The results sho
PMID 24732301

Japanese Journal

Diacylglycerol Signaling Pathway in Pancreatic β-Cells : An Essential Role of Diacylglycerol Kinase in the Regulation of Insulin Secretion (Recent Progress in the Research of Insulin Secretion)

Kaneko Yukiko K.,Ishikawa Tomohisa
Biological & pharmaceutical bulletin 38(5), 669-673, 2015-05
NAID 40020440656

Foods Highly Containing Diacylglycerol:Summary

Food Safety Commission of Japan
Food Safety 3(2), 65-66, 2015
… The Food Safety Commission of Japan (FSCJ) conducted a risk assessment on foods highly containing diacylglycerol (DAG) (hereinafter referred to as DAG foods), based on results from various studies. …
NAID 130005084366

Considerations on Glycidol and Its Fatty Acid Esters in Foods:Executive Summary

Food Safety Commission of Japan
Food Safety 3(2), 67-69, 2015
… As a part of a safety assessment of foods highly containing diacylglycerol (DAG), the Food Safety Commission of Japan (FSCJ) conducted a safety assessment of glycidol and its fatty acid esters (GE) in foods based on results from various studies. …
NAID 130005084363

Related Pictures

★リンクテーブル★

リンク元	「ジアシルグリセロール」
拡張検索	「glycosylphosphatidylinositol diacylglycerol-lyase」「CDPdiacylglycerol-serine O-phosphatidyltransferase」「diacylglycerol cholinephosphotransferase」「diacylglycerol kinase」