Identification of a nonmucin glycoprotein (gp-340) from a purified respiratory mucin preparation: evidence for an association involving the MUC5B mucin

Glycobiology. 2001 Nov;11(11):969-77. doi: 10.1093/glycob/11.11.969.


Rate-zonal centrifugation of a reduced and alkylated respiratory mucin preparation identified a protein-rich fraction. This was subjected to trypsin treatment and one of the many liberated peptides was purified and its N-terminal sequence determined. The peptide was identical to a 14 amino acid sequence from the scavenger receptor cysteine-rich domain containing glycoprotein gp-340. A polyclonal antiserum, raised against the peptide, stained the serous cells in the submucosal glands of human tracheal tissue. The glycoprotein was purified from respiratory mucus by density-gradient centrifugation, gel chromatography, and anion exchange chromatography. The molecule exhibited a heterogeneous distribution of buoyant density (1.28-1.46 g/ml) that overlapped with the gel-forming mucins, was included on Sepharose CL-2B and was quite highly anionic. SDS-PAGE indicated a mass greater than 208 kDa and measurements performed across the molecular size distribution indicated an average M(r) of 5 x 10(5) with a range of M(r) from 2 x 10(5) to 1 x 10(6). Gel chromatography of respiratory mucus extracts ("associative" and "dissociative") indicated that this glycoprotein forms complexes that may involve the large gel-forming mucins MUC5AC and MUC5B. Rate zonal centrifugation suggested such complexes are more likely to involve MUC5B rather than MUC5AC mucins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Humans
  • Immunohistochemistry
  • Macromolecular Substances
  • Monosaccharides / analysis
  • Mucin-5B
  • Mucins / chemistry*
  • Mucins / isolation & purification
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / isolation & purification
  • Receptors, Immunologic / chemistry*
  • Receptors, Immunologic / genetics
  • Receptors, Immunologic / isolation & purification
  • Sequence Homology, Amino Acid
  • Trachea / chemistry


  • MUC5B protein, human
  • Macromolecular Substances
  • Monosaccharides
  • Mucin-5B
  • Mucins
  • Peptide Fragments
  • Receptors, Immunologic
  • glycoprotein 340