In enzymology, a geranylgeranylglycerol-phosphate geranylgeranyltransferase () is an enzyme that catalyzes the chemical reaction geranylgeranyl diphosphate + sn-3-O-(geranylgeranyl)glycerol 1-phosphate diphosphate + 2,3-bis-O-(geranylgeranyl)glycerol 1-phosphate Thus, the two substrates of this enzyme are geranylgeranyl diphosphate and sn-3-O-(geranylgeranyl)glycerol 1-phosphate, whereas its two products are diphosphate and 2,3-bis-O-(geranylgeranyl)glycerol 1-phosphate. This enzyme belongs to the family of transferases, specifically those transferring aryl groups or alkyl groups other than methyl groups. The systematic name of this enzyme class is geranylgeranyl diphosphate:sn-3-O-(geranylgeranyl)glycerol 1-phosphate geranylgeranyltransferase. Other names in common use include geranylgeranyloxyglycerol phosphate geranylgeranyltransferase, and geranylgeranyltransferase II. Structural studies As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and . References EC 2.5.1 Enzymes of known structure