Involved in the biosynthesis of glucosylglycerate. Catalyzes the dephosphorylation of glucosyl-3-phosphoglycerate (GPG) and mannosyl-3-phosphoglycerate (MPG) to glucosylglycerate (GG) and mannosylglycerate (MG), respectively. (2R)-2-O-(alpha-D-glucopyranosyl)-3-phospho-glycerate + H2O = (2R)-2-O-(alpha-D-glucopyranosyl)-glycerate + phosphate 2-O-(alpha-D-mannosyl)-3-phosphoglycerate + H2O = (2R)-2-O-(alpha-D-mannosyl)-glycerate + phosphate Divalent metal cations. Can use Mg(2+), Co(2+) and, to a lesser extent, Mn(2+) ions. Optimum pH is 7. Optimum temperature is 85 degrees Celsius. Monomer. Belongs to the HAD-like hydrolase superfamily. MPGP family.