Galactolipid galactosyltransferase

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In enzymology, a galactolipid galactosyltransferase (EC 2.4.1.184) is an enzyme that catalyzes the chemical reaction

2 3-(beta-D-galactosyl)-1,2-diacyl-sn-glycerol $\rightleftharpoons$ 3-[alpha-D-galactosyl-(1->6)-beta-D-galactosyl]-1,2-diacyl-sn- glycerol + 1,2-diacyl-sn-glycerol

Hence, this enzyme has one substrate, 3-(beta-D-galactosyl)-1,2-diacyl-sn-glycerol, but 3 products: [[3-[alpha-D-galactosyl-(1->6)-beta-D-galactosyl]-1,2-diacyl-sn-]], glycerol, and 1,2-diacyl-sn-glycerol.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is 3-(beta-D-galactosyl)-1,2-diacyl-sn-glycerol:mono-3-(beta-D-galactos yl)-1,2-diacyl-sn-glycerol beta-D-galactosyltransferase. Other names in common use include galactolipid-galactolipid galactosyltransferase, galactolipid:galactolipid galactosyltransferase, interlipid galactosyltransferase, GGGT, DGDG synthase (ambiguous), and digalactosyldiacylglycerol synthase (ambiguous). This enzyme participates in glycerolipid metabolism.

[edit] References

IUBMB entry for 2.4.1.184
BRENDA references for 2.4.1.184 (Recommended.)
PubMed references for 2.4.1.184
PubMed Central references for 2.4.1.184
Google Scholar references for 2.4.1.184
Dorne A-J, Block MA, Joyard J and Douce R (1982). "The galactolipid-galactolipid galactosyltransferase is located on the outer surface of the outer-membrane of the chloroplast envelope". FEBS Lett. 145: 30–34.
Dorne A-J and Douce R (1986). "Localization of galactolipid:galactolipid galactosyltransferase and acyltransferase in outer envelope membrane of spinach chloroplasts". Biochim. Biophys. Acta 877: 281–289.
Heemskerk JWM, Jacobs FHH and Wintermans JFGM (1988). "UDPgalactose-independent synthesis of monogalactosyldiacylglycerol An enzymatic activity of the spinach chloroplast envelope". Biochim. Biophys. Acta 961: 38–47.
Kelly AA, Froehlich JE, Dormann P (2003). "Disruption of the two digalactosyldiacylglycerol synthase genes DGD1 and DGD2 in Arabidopsis reveals the existence of an additional enzyme of galactolipid synthesis". Plant. Cell. 15: 2694–706. PMID 14600212.
Benning C, Ohta H (2005). "Three enzyme systems for galactoglycerolipid biosynthesis are coordinately regulated in plants". J. Biol. Chem. 280: 2397–400. PMID 15590685.