title: Cloning and analysis of cDNA encoding a major airway glycoprotein, human tracheobronchial mucin (MUC5).
abstract: Two unique nucleotide probes for human tracheobronchial mucin glycoprotein (TBM) were generated via polymerase chain reaction with degenerate primers deduced from the TBM:TR-3A tryptic peptide sequence and were used to isolate a 3.6 kilobase cDNA, clone NP3a, from a human nasal polyp cDNA library. Clone NP3a was localized to chromosome 11 and contained a 3168 nucleotide open reading frame which encoded three TBM peptide fragments, thus confirming that clone NP3a partially encodes TBM. TBM also contains five tandem repeats of TTVGP/S and an octapeptide GQCGTCTN, which is conserved in human intestinal mucin MUC2 and rat intestinal mucin-like protein (MLP) suggesting that this sequence has a functional significance for secreted mucins. TBM has amino acid similarity to the cysteine-rich domains at the carboxyl termini of MUC2, rat MLP, bovine and porcine submaxillary mucins, and human von Willebrand factor. Strikingly, a large percentage of the cysteine residues in the overlaps are highly conserved: 90% in MUC2 and von Willebrand factor, 80% of bovine submaxillary mucin, 70% in porcine submaxillary mucin, and 64% in rat MLP, suggesting that conserved cysteines may be important for the tertiary structure of secreted glycoproteins. These studies demonstrate that clone NP3a is a candidate for MUC5, making it the only human mucin gene reported to date whose gene product has been isolated from airway secretions.
authors.affiliation: Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010.
authors.forename: D
authors.initials: D
authors.lastname: Meezaman
authors.forename: P
authors.initials: P
authors.lastname: Charles
authors.forename: E
authors.initials: E
authors.lastname: Daskal
authors.forename: M H
authors.initials: MH
authors.lastname: Polymeropoulos
authors.forename: B M
authors.initials: BM
authors.lastname: Martin
authors.forename: M C
authors.initials: MC
authors.lastname: Rose
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D001980:Bronchi / Q000378:metabolism*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018076:DNA, Complementary; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D055257:Mucin-5B; D009077:Mucins / Q000235:genetics* / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D014132:Trachea / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; C524578:MUC5B protein, human; D055257:Mucin-5B; D009077:Mucins; D012313:RNA