This group of bacterial proteins is involved in the synthesis of O-antigen, a lipopolysaccharide found in the outer membrane in gram-negative bacteria. This family includes O-antigen ligases such as E. coli RfaL [1].

1: Comparison of lipopolysaccharide biosynthesis genes rfaK, rfaL, rfaY, and rfaZ of Escherichia coli K-12 and Salmonella typhimurium. Klena JD, Pradel E, Schnaitman CA; J Bacteriol. 1992;174:4746-4752. PMID:1624462