Prenyltransferase that catalyzes the transfer of the geranylgeranyl moiety of geranylgeranyl diphosphate (GGPP) to the C3 hydroxyl of sn-glycerol-1-phosphate (G1P). This reaction is the first ether-bond-formation step in the biosynthesis of archaeal membrane lipids. Cannot use sn-glycerol-3-phosphate (G3P) as substrate. (2E,6E,10E)-geranylgeranyl diphosphate + sn-glycerol 1-phosphate = diphosphate + sn-3-O-(geranylgeranyl)glycerol 1-phosphate Cannot use Mn(2+) or Zn(2+). Inhibited by high concentrations of magnesium (>10 mM) and by EDTA in vitro. Optimum pH is about 7.0. Active from pH 6 to 9. Optimum temperature is 55 degrees Celsius. Membrane lipid metabolism; glycerophospholipid metabolism. Homodimer. Belongs to the GGGP/HepGP synthase family. Group II subfamily.