• Forms type 1 LacNAc chains (Galβ1-3GlcNAc) primarily in cell types derived from the endoderm (lung, thyroid, pancreas etc.).
• Helps form Lewis^a and Lewis^b antigens, and also sialyl-Le^a (CA19-9) and disialyl-Le^a (FH7).
• Three enzymes may form the type I LacNAc chain (B3GalT-1, -2 and -5). The expression pattern of these three enzymes vary with B3Gal-T1 being restricted to brain as well as intestine and colon; B3Gal-T2 in heart, brain, and bone marrow; and B3Gal-T5 in the gastrointestinal tract.
• B3Gal-T1 showed activity toward simple βGlcNAc saccharides and lactoseries glycosphingolipids, but not N-glycans on ovalbumin and asialo-agalacto-fetuin.
• B3Gal-T2 shows activity with both simple βGlcNAc saccharides, βGlcNAc terminating lactoseries glycosphingolipids, and ovalbumin and asialoagalacto-fetuin N-glycoprotein acceptors.
• B3Gal-T5 produces type 1 chain linkage in glycolipids and core-3 O-glycans, but not N-linked glycoproteins.
• Thus, multiple enzymes act on GSLs, but only B3GalT2 is the primary enzyme modifying N-glycans.