Mucin-5AC

Mucins are heavily glycosylated glycoproteins, which constitute the major components of mucus which cover the surface of epithelial tissues. Nine distinct epithelial mucin genes (Muc-1, 2, 3, 4, 5AC, 5B, 6, 7 and 8) have been identified. Various immunohistochemical and in situ hybridization studies have shown that these mucins are differentially expressed in epithelia with cell-type specificity. Muc-5AC and Muc-6 glycoproteins are the first two mucins found in superficial epithelium and Muc-6 glycoprotein is found in the deep glands. The epitope is destroyed by beta-mercaptoethanol and proteases but not by periodate treatment. Antibody to gastric mucin M1 reacts with the gastric epithelium of normal human gastrointestinal tract as well as with the precancerous and cancerous colon, but not with normal adult colon. It also reacts with fetal colonic mucosa. Resurgence of gastric mucin reactivity during colonic carcinogenesis is due to re-expression of the peptide core of gastric (or fetal colonic) mucins.