MUCUS GLYCOPROTEINS FROM PIG GASTRIC-MUCOSA - DIFFERENT MUCINS ARE PRODUCED BY THE SURFACE EPITHELIUM AND THE GLANDS

An antibody (PGM2B) recognizing a pig gastric-mucin apoprotein reacts with the surface epithelium of pig gastric mucosa. Virtually no reacti vity was observed over the mucin-producing cells in the glands, which were recognized by the GlcNAc-selective Griffonia simplicifolia II (GS B-II) lectin. Mucins from the glandular tissue of the cardiac region, corpus and antrum were purified using isopycnic density-gradient centr ifugation in CsCl/guanidinium chloride. In the cardiac region, two maj or mucin populations at 1.5 and 1.4 g/ml were identified. The high-den sity population reacted preferentially with the PGM2B antibody and res embled mucins from the surface epithelium of this region, whereas the low-density population reacted strongly with the GSA-II lectin and app eared to originate from the glands. In the glandular tissue of corpus, a component with strong GSA-II lectin reactivity, which was distinctl y different from the surface mucins from this region, was found at 1.4 g/ml, thus resembling the gland component from the cardiac region. Mu cins from antrum glandular tissue contained at least two GSA-II lectin -reactive populations banding at 1.5 and 1.4 g/ml, respectively. Gland mucins from all regions were large oligomeric glycoproteins and heter ogeneous with respect to charge properties, as shown by using rate-zon al centrifugation and ion-exchange HPLC, respectively. Gel chromatogra phy of mucin glycopeptides showed that gland mucins from antrum and co rpus contained significantly longer glycosylated domains than those fr om the surface mucosa. Thus, mucins from pig gastric glandular tissue comprise a number of large and oligomeric glycoproteins that differ fr om those from the surface epithelium in buoyant density, apoprotein st ructure and carbohydrate substitution.