Biosynthesis of human colonic mucin: Muc2 is the prominent secretory mucin

Gastroenterology. 1994 Nov;107(5):1352-63. doi: 10.1016/0016-5085(94)90537-1.


Background/aims: Human colonic epithelium produces large amounts of mucin. The aim of this study was to examine mucin biosynthesis in the human colon.

Methods: Human colonic mucin was isolated using CsCl density gradients, and polyclonal antiserum was raised. Biosynthesis of colonic mucins was studied by labeling colonic explants with 35S-labeled amino acids or [35S]sulfate and subsequent immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).

Results: The polyclonal antiserum specifically recognized colonic mucin, primarily reacting with peptide epitopes. Biosynthetic pulse/chase experiments showed a 35S-amino acid-labeled mucin precursor of about 600 kilodaltons, which was converted into a mature, glycosylated, and sulfated mucin and subsequently secreted into the medium. This mature mucin comigrated with isolated colonic mucin with an apparent molecular weight of 550 kilodaltons on SDS-PAGE, whereas gel filtration indicated that the molecular weight is actually much larger. Independent immunoprecipitation with an anti-Muc2 antiserum showed cross-reactivity with the 600-kilodalton precursor.

Conclusions: These results show the biosynthesis of a secretory colonic mucin for the first time. This mucin is synthesized as a precursor protein of approximately 600 kilodaltons, which, after glycosylation, is secreted as a glycoprotein with an apparent molecular weight of 550 kilodaltons on SDS-PAGE. It is very likely that this mucin is Muc2.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Colon / metabolism*
  • Electrophoresis, Polyacrylamide Gel
  • Glycosylation
  • Humans
  • Immune Sera
  • Intestinal Mucosa / metabolism
  • Molecular Weight
  • Mucin-2
  • Mucins / analysis
  • Mucins / biosynthesis*
  • Mucins / metabolism
  • Precipitin Tests
  • Protein Precursors / biosynthesis


  • Immune Sera
  • MUC2 protein, human
  • Mucin-2
  • Mucins
  • Protein Precursors