THE GLYCOSYLATION OF RAT INTESTINAL MUC2 MUCIN VARIES BETWEEN RAT STRAINS AND THE SMALL AND LARGE-INTESTINE - A STUDY OF O-LINKED OLIGOSACCHARIDES BY A MASS-SPECTROMETRIC APPROACH

The large glycosylated domains obtained from the rat intestinal mucin Muc2 were isolated from the large and small intestine of the inbred ra t strains GOT-W and GOT-BW. The expression of the rat Muc2 in the larg e intestine was confirmed immunochemically and by Northern blotting. R eleased oligosaccharides were structurally characterized by gas chroma tography-mass spectrometry (neutral and sialylated species) or by tand em mass spectrometry (sulfated species), and a total of 63 structures was assigned. The large intestinal oligosaccharides were found to be i dentical between the strains, while the small intestinal glycosylation differed. Until now, detailed structural analysis of oligosaccharides isolated from a single mucin core or mucin domain with different orig in have not been performed, and the information of different mucin gly coforms has been limited to immunochemistry. Blood group A-determinant s (Gal-NAc alpha 1-3(Fuc alpha 1-2)Gal beta 1-, and structures related to the blood group Sd(a)/Cad-related epitope NeuAc/NeuGc alpha 1-3(Ga lNAc beta 1-4)Gal beta 1-were found in GOT-BW small intestine, and als o in both large intestines. Blood group H-determinants and NeuAc/NeuGc alpha 1-3Gal beta 1- were found in all samples. Core 1 (Gal beta 1-3G alNAc alpha 1-), core 2 (Gal beta 1-3(GlcNAc beta 1-6)GalNAc alpha 1-) , core 3 (GlcNAc beta 1-3GalNAc alpha 1-), and core 4 (GlcNAc beta 1-3 (GlcNAc beta 1-6)GalNAc alpha 1- were also found in all the samples. T he large intestine were enriched in sulfated oligosaccharides and the small intestine contained higher amounts of sialylated species. Sulfat ion were found exclusively on C-6 of GlcNAc.