MUC4 is a major component of salivary mucin MG1 secreted by the human submandibular gland.

High molecular weight salivary mucin (MG1) is an important component of saliva, contributing to the lubricative and tissue-protective functions of this biological fluid. We have shown previously that the human mucin gene MUC5B is expressed at high levels in sublingual gland and is a significant constituent of MG1. Since many epithelia express multiple mucin genes, it seemed likely that MG1 in salivary secretions is also a heterogeneous mixture of mucin gene products. The aim of this study was to determine whether MUC4, a mucin shown in Northern blotting experiments to be expressed in salivary glands, was a significant protein component of MG1 in salivary secretions. Two cDNA clones containing MUC4 tandem repeats were isolated from a human submandibular gland cDNA library. In addition, recombinant MUC4 produced in a bacterial expression system cross-reacted with an antibody directed against deglycosylated MG1. This shows conclusively that human salivary mucin MG1 contains both MUC5B and MUC4 gene products suggesting that each mucin may perform distinct functions in the oral cavity.

[1]  D. Nunes,et al.  Molecular characterization of a major high molecular weight mucin from human sublingual gland. , 1997, Glycobiology.

[2]  I. van Seuningen,et al.  Genomic Organization of the 3′ Region of the Human Mucin GeneMUC5B * , 1997, The Journal of Biological Chemistry.

[3]  J. Kasperbauer,et al.  Mucin mRNA Expression in Normal and Vasomotor Inferior Turbinates , 1997, American journal of rhinology.

[4]  I. Gipson,et al.  Mucin genes expressed by human female reproductive tract epithelia. , 1997, Biology of reproduction.

[5]  H. Wandall,et al.  Identification of a major human high molecular weight salivary mucin (MG1) as tracheobronchial mucin MUC5B. , 1997, Glycobiology.

[6]  T. Inatomi,et al.  Expression of secretory mucin genes by human conjunctival epithelia. , 1996, Investigative ophthalmology & visual science.

[7]  F. Oppenheim,et al.  Molecular cloning of a novel high molecular weight mucin (MG1) from human sublingual gland. , 1995, Biochemical and biophysical research communications.

[8]  D. Verwoerd,et al.  Distinct populations of high-M(r) mucins secreted by different human salivary glands discriminated by density-gradient electrophoresis. , 1995, The Biochemical journal.

[9]  S. Gendler,et al.  Epithelial mucin genes. , 1995, Annual review of physiology.

[10]  L. Tabak.  In defense of the oral cavity: structure, biosynthesis, and function of salivary mucins. , 1995, Annual review of physiology.

[11]  M. Gross,et al.  Molecular cloning and chromosomal localization of a novel human tracheo-bronchial mucin cDNA containing tandemly repeated sequences of 48 base pairs. , 1991, Biochemical and biophysical research communications.

[12]  M. Levine,et al.  Immunochemistry of high molecular-weight human salivary mucin. , 1990, Archives of oral biology.

[13]  M. Levine,et al.  Biochemical and biophysical comparison of two mucins from human submandibular-sublingual saliva. , 1987, Archives of biochemistry and biophysics.

[14]  P. Chomczyński,et al.  Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. , 1987, Analytical biochemistry.

[15]  L. Tabak,et al.  Structural Aspects of Salivary Glycoproteins , 1987, Journal of dental research.