ENZYME

ENZYME entry: EC 2.4.1.241

Accepted Name

Digalactosyldiacylglycerol synthase.

Alternative Name(s)

DGDG synthase.

UDP-galactose-dependent DGDG synthase.

UDP-galactose-dependent digalactosyldiacylglycerol synthase.

UDP-galactose:MGDG galactosyltransferase.

Reaction catalysed

UDP-galactose + 3-(beta-D-galactosyl)-1,2-diacyl-sn-glycerol <=> UDP + 3-(alpha-D-galactosyl-(1->6)-beta-D-galactosyl)-1,2-diacyl-sn-glycerol

Cofactor(s)

Magnesium.

Comment(s)

Diacylglycerol cannot serve as an acceptor molecule for galactosylation as in the reaction catalyzed by EC 2.4.1.46.
When phosphate is limiting, phospholipids in plant membranes are reduced but these are replaced, at least in part, by the glycolipids digalactosyldiacylglycerol (DGDG) and sulfoquinovosyldiacylglycerol.
While both DGD1 and DGD2 are increased under phosphate-limiting conditions, DGD2 does not contribute significantly under optimal growth conditions.
DGD2 is responsible for the synthesis of DGDG molecular species that are rich in C16 fatty acids at sn-1 of diacylglycerol whereas DGD1 leads to molecular species rich in C18 fatty acids.
The enzyme has been localized to the outer side of chloroplast envelope membranes.

Cross-references

BRENDA

EC2PDB

ExplorEnz

PRIAM enzyme-specific profiles

KEGG Ligand Database for Enzyme Nomenclature

IUBMB Enzyme Nomenclature