Probable galacturonosyltransferase

GT8_like_1 represents a subfamily of GT8 with unknown function. A subfamily of glycosyltransferase family 8 with unknown function: Glycosyltransferase family 8 comprises enzymes with a number of known activities; lipopolysaccharide galactosyltransferase lipopolysaccharide glucosyltransferase 1, glycogenin glucosyltransferase and inositol 1-alpha-galactosyltransferase. It is classified as a retaining glycosyltransferase, based on the relative anomeric stereochemistry of the substrate and product in the reaction catalyzed.

A4GalT_like proteins catalyze the addition of galactose or glucose residues to the lipooligosaccharide (LOS) or lipopolysaccharide (LPS) of the bacterial cell surface. The members of this family of glycosyltransferases catalyze the addition of galactose or glucose residues to the lipooligosaccharide (LOS) or lipopolysaccharide (LPS) of the bacterial cell surface. The enzymes exhibit broad substrate specificities. The known functions found in this family include: Alpha-1,4-galactosyltransferase, LOS-alpha-1,3-D-galactosyltransferase, UDP-glucose:(galactosyl) LPS alpha1,2-glucosyltransferase, UDP-galactose: (glucosyl) LPS alpha1,2-galactosyltransferase, and UDP-glucose:(glucosyl) LPS alpha1,2-glucosyltransferase. Alpha-1,4-galactosyltransferase from N. meningitidis adds an alpha-galactose from UDP-Gal (the donor) to a terminal lactose (the acceptor) of the LOS structure of outer membrane. LOSs are virulence factors that enable the organism to evade the immune system of host cells. In E. coli, the three alpha-1,2-glycosyltransferases, that are involved in the synthesis of the outer core region of the LPS, are all members of this family. The three enzymes share 40 % of sequence identity, but have different sugar donor or acceptor specificities, representing the structural diversity of LPS.

Members of glycosyltransferase family 8 (GT-8) are involved in lipopolysaccharide biosynthesis and glycogen synthesis. Members of this family are involved in lipopolysaccharide biosynthesis and glycogen synthesis. GT-8 comprises enzymes with a number of known activities: lipopolysaccharide galactosyltransferase, lipopolysaccharide glucosyltransferase 1, glycogenin glucosyltransferase, and N-acetylglucosaminyltransferase. GT-8 enzymes contains a conserved DXD motif which is essential in the coordination of a catalytic divalent cation, most commonly Mn2+.

The C-terminal domain of HUGT1-like is highly homologous to the GT 8 family. C-terminal domain of glycoprotein glucosyltransferase (UGT). UGT is a large glycoprotein whose C-terminus contains the catalytic activity. This catalytic C-terminal domain is highly homologous to Glycosyltransferase Family 8 (GT 8) and contains the DXD motif that coordinates donor sugar binding, characteristic for Family 8 glycosyltransferases. GT 8 proteins are retaining enzymes based on the relative anomeric stereochemistry of the substrate and product in the reaction catalyzed. The non-catalytic N-terminal portion of the human UTG1 (HUGT1) has been shown to monitor the protein folding status and activate its glucosyltransferase activity.