title: The carboxyl-terminal sequence of the human secretory mucin, MUC6. Analysis Of the primary amino acid sequence.
abstract: The distribution of MUC6 suggests that its primary function is protection of vulnerable epithelial surfaces from damaging effects of constant exposure to a wide range of endogenous caustic or proteolytic agents. A combination of genomic, cDNA. and 3' rapid amplification of cDNA ends techniques was used to isolate the carboxyl-terminal end of MUC6. The 3' nontandem repeat region contained 1083 base pairs of coding sequence (361 amino acids) followed by 632 base pairs of 3'-untranslated region. The coding sequence consists of two distinct regions; region 1 contained the initial 270 amino acids (62% Ser-Thr-Pro with no Cys residues), and region 2 contained the COOH-terminal 91 amino acids (22% Ser-Thr-Pro with 12% Cys). Although region 1 had no homology to any sequences in GenBank, region 2 had approximately 25% amino acid homology to the COOH-terminal regions of human mucins MUC2, -5, and -5B and von Willebrand factor. The shortness of region 2 would leave little of the peptide backbone exposed to a potentially hostile environment. Antibody studies suggest that MUC6 in its native form exists as a disulfide-bonded multimer. The conservation of the 11 cysteine positions in region 2 suggests the importance of this short region to mucin polymerization.
authors.affiliation: Gastrointestinal Research Laboratory, Department of Veterans Affairs Medical Center and the Division of Gastroenterology, University of California, San Francisco, California 94121, USA.
authors.forename: N W
authors.initials: NW
authors.lastname: Toribara
authors.forename: S B
authors.initials: SB
authors.lastname: Ho
authors.forename: E
authors.initials: E
authors.lastname: Gum
authors.forename: J R
authors.initials: JR
authors.lastname: Gum
authors.forename: P
authors.initials: P
authors.lastname: Lau
authors.forename: Y S
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D019281:Dimerization; D006801:Humans; D008969:Molecular Sequence Data; D009077:Mucins / Q000737:chemistry*; D014841:von Willebrand Factor / Q000737:chemistry
chemical_list: D009077:Mucins; D014841:von Willebrand Factor