This family consists of examples of mannosyl-3-phosphoglycerate synthase (MPGS), which together with mannosyl-3-phosphoglycerate phosphatase (MPGP) EC:2.4.1.217, comprises a two-step pathway for mannosylglycerate biosynthesis. Mannosylglycerate is a compatible solute that tends to be restricted to extreme thermophiles of archaea and bacteria. Note that in Rhodothermus marinus, this pathway is one of two; the other is condensation of GDP-mannose with D-glycerate by mannosylglycerate synthase.