The filamentous brush border glycocalyx, a mucin-like marker of enterocyte hyper-polarization

Eur J Biochem. 1995 Mar 1;228(2):323-31.


The probably sole constituent of the filamentous brush border glycocalyx, which has been defined on the basis of electron microscopic data as a set of filaments radiating from the tip of rabbit intestinal brush border microvilli, has been purified. It consists of a mucin-type glycoprotein that can be solubilized by either Triton extraction or papain treatment of the brush border membrane vesicles but is insensitive to phosphatidylinositol phospholipase C. The detergent- and papain-solubilized forms both have the same apparent molecular mass of 400 kDa (SDS/PAGE). This suggests that the filamentous brush border glycocalyx may be anchored to the membrane by a small hydrophobic peptidic tail. Ser, Thr, Pro and Ala amount to 65% of the protein core amino acid residues. The glycosidic moiety, which amounts to 73% of the molecular mass, has high O-acetylated sialic acid contents. A monoclonal antibody (3A4) raised against the purified material was produced which specifically recognized the 400-kDa band by immunoprecipitation and immunoblotting, and the filamentous brush border glycocalyx of villus enterocytes when jejunum sections were immunolabelled. The 3A4 determinant was identified with a filamentous brush border glycocalyx-specific carbohydrate structure containing an O-acetylated sialic acid. The fact that the labeled glycocalyx was anchored entirely in a membrane microdomain at the tip of the microvilli shows that mature enterocytes are hyper-polarized epithelial cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / analysis
  • Animals
  • Antibodies, Monoclonal / immunology
  • Epitopes
  • Glycoconjugates / isolation & purification
  • Glycoproteins / analysis
  • Glycoproteins / immunology
  • Glycoproteins / isolation & purification*
  • Humans
  • Intestinal Mucosa / chemistry*
  • Mice
  • Mice, Inbred BALB C
  • Molecular Weight
  • Mucins / analysis
  • Polysaccharides / analysis
  • Polysaccharides / immunology
  • Polysaccharides / isolation & purification*
  • Rabbits


  • Amino Acids
  • Antibodies, Monoclonal
  • Epitopes
  • Glycoconjugates
  • Glycoproteins
  • Mucins
  • Polysaccharides