Part of the type 2Gn receptor polysaccharide (RPS) biosynthesis locus. Essential for cell surface RPS production, and for synthesis of the host-like GalNAc beta 1-3Gal (Gn) motif of the RPS. Probably encodes a 1-3Gal alpha transferase. The cell wall polysaccharides of some oral streptococci act as receptors for the lectin-like surface adhesins on other members of the oral biofilm community, especially type 2 fimbriated strains of Actinomyces naeslundii, allowing colonization of the human tooth surface. Recognition of these receptor polysaccharides (RPS) depends on the presence of a host-like motif, either GalNAc beta 1-3Gal (Gn) or Gal beta 1-3GalNAc (G), within the oligosaccharide repeating units of different RPS structural types. Type 2Gn RPS of S.gordonii strain 38 and type 2G RPS of S.mitis strain J22 are composed of heptasaccharide repeats that are identical except for their host-like motifs. This mimicry of the host glycoconjugates may help the bacteria evade the immune system. Stealth proteins are part of a protein family that is conserved from bacteria to higher eukaryotes. Family members were first identified in microbes as proteins that help pathogens to elude the host innate immune system. Microbial stealth proteins are involved in the biosynthesis of exopolysaccharides. Stealth proteins are predicted to function as hexose-1-phosphoryltransferases. Belongs to the stealth family.