Formation of the extracellular mucous matrix of olfactory neuroepithelium: identification of partially glycosylated and nonglycosylated precursors of olfactomedin.
Olfactomedin is the major glycoprotein of the extracellular mucous matrix of frog olfactory neuroepithelium. It is responsible for the primary architecture of this extracellular matrix by forming via intermolecular disulfide bonds polymers, which are covered with evenly spaced carbohydrate groups. To study glycosylation of olfactomedin, we raised antibodies against the mature protein and antibodies against a region adjacent to an N-linked glycosylation site near its amino terminus. The latter antibodies cannot bind when this site is glycosylated and reveal precursors of olfactomedin in the perinuclear regions of Bowman's glands. In contrast, antiserum against the mature protein stains acinar regions of glands and the ciliary surface. Enzymatic deglycosylation of olfactomedin shows stepwise removal of carbohydrate and reveals a 51-kDa deglycosylated form. Our results indicate that, prior to secretion, most, if not all, of the six potential N-linked glycosylation sites of olfactomedin are glycosylated with carbohydrate moieties of about 8-10 sugar residues.
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Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710.
Anholt
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D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D004848:Epithelium / Q000737:chemistry / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism*; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D006031:Glycosylation; D007150:Immunohistochemistry; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000378:metabolism; D008969:Molecular Sequence Data; D009831:Olfactory Mucosa / Q000737:chemistry / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011892:Rana catesbeiana
D006023:Glycoproteins; D011498:Protein Precursors; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase