In Gram-negative bacteria the enzyme is involved in biosynthesis of ADP-L-glycero-¦Â-D-manno-heptose, which is utilized for assembly of the lipopolysaccharide inner core. In Gram-positive bacteria the enzyme is involved in biosynthesis of GDP-D-glycero-¦Á-D-manno-heptose, which is required for assembly of S-layer glycoprotein.