title: Unique glycosylation of three keratan sulfate proteoglycan isoforms.
abstract: Recent work demonstrates isoforms of bovine corneal keratan sulfate proteoglycan containing structurally unique core proteins of 25 and 37 kDa (Funderburgh, J., and Conrad, G. (1990) J. Biol. Chem. 265, 8297-8303). In the current study, two forms (37A and 37B) of the 37-kDa protein were separated by ion-exchange chromatography after removal of keratan sulfate with endo-beta-galactosidase. Keratan sulfate linkage sites in core proteins were labeled with UDP-[3H]galactose using galactosyltransferase. Labeled proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and analyzed by tryptic digestion and reversed-phase chromatography. The 37A protein has three keratan sulfate-linkage sites, and the 37B and 25-kDa proteins each contain one linkage site. Reversed-phase tryptic maps of the three proteins differed in total peptide profile and in glycosylated peptides labeled with periodate-[3H]-NaBH4. Tryptic mapping of the two 37-kDa isoforms after deglycosylation showed differences in total tryptic peptides, in peptides labeled with [14C]iodoacetic acid, and in peptides recognized by antibodies to a mixture of the 37-kDa cores. Antibody to a synthetic peptide with N-terminal sequence obtained from mixed 37-kDa cores reacted exclusively with the 37B isoform. These results show that bovine corneal keratan sulfate proteoglycan has three different core proteins each with distinct glycosylation and unique primary structure.
authors.affiliation: Division of Biology, Kansas State University, Manhattan 66506.
authors.forename: J L
authors.initials: JL
authors.lastname: Funderburgh
authors.forename: M L
authors.initials: ML
authors.lastname: Funderburgh
authors.forename: M M
authors.initials: MM
authors.lastname: Mann
authors.forename: G W
authors.initials: GW
authors.lastname: Conrad
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002417:Cattle; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism*; D002852:Chromatography, Ion Exchange; D003315:Cornea / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006026:Glycoside Hydrolases; D006031:Glycosylation; D007632:Keratan Sulfate / Q000378:metabolism*; D000071234:Lumican; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D014357:Trypsin; D001616:beta-Galactosidase
chemical_list: D011508:Chondroitin Sulfate Proteoglycans; D000071234:Lumican; D007632:Keratan Sulfate; D006026:Glycoside Hydrolases; C026093:keratan-sulfate endo-1,4-beta-galactosidase; D001616:beta-Galactosidase; D014357:Trypsin