The enzyme is involved in biosynthesis of 2-O-(¦Á-D-glucopyranosyl)-D-glycerate via the two-step pathway in which glucosyl-3-phosphoglycerate synthase catalyses the conversion of GDP-glucose and 3-phospho-D-glycerate into 2-O-(¦Á-D-glucopyranosyl)-3-phospho-D-glycerate, which is then converted to 2-O-(¦Á-D-glucopyranosyl)-D-glycerate by EC 3.1.3.85 glucosyl-3-phosphoglycerate phosphatase. The activity is dependent on divalent cations (Mn2+, Co2+, or Mg2+). The enzyme from Persephonella marina shows moderate flexibility on the sugar donor concerning the nucleotide moiety (UDP-glucose, ADP-glucose, GDP-glucose) but is strictly specific for glucose. The enzyme is also strictly specific for 3-phospho-D-glycerate as acceptor [1]. The enzyme from Methanococcoides burtonii is strictly specific for GDP-glucose and 3-phospho-D-glycerate [2]. This enzyme catalyses the first glucosylation step in methylglucose lipopolysaccharide biosynthesis in mycobacteria [4,5].