Isoforms of corneal keratan sulfate proteoglycan.
Bovine corneal keratan sulfate proteoglycan was found to contain three major protein components. Two proteins (37 and 25 kDa) were released from the proteoglycan by endo-beta-galactosidase, N-glycanase, or chemical deglycosylation. A smaller protein (20 kDa), not covalently linked to keratan sulfate, co-purified with the proteoglycan by conventional and high performance ion exchange chromatography, by ethanol precipitation, and by affinity purification on columns of monoclonal antibody to keratan sulfate, but could be separated from the proteoglycan by gel filtration chromatography in dissociative agents. The three proteins produced different fragmentation patterns on sodium dodecyl sulfate-polyacrylamide gel electrophoresis after digestion with V8 protease, and each had unique two-dimensional tryptic peptide maps. The N-terminal amino acid sequence of the core proteins differed. In addition, the proteoglycans containing these proteins differed in molecular size, suggesting different levels of glycosylation of the two core proteins. Similarity of the core proteins was suggested by similar amino acid composition, similarities in tryptic maps, and antigenic cross-reactivity. Corneal keratan sulfate proteoglycan, therefore, seems to occur in two different, but related, forms whose core proteins may represent members of a homologous family.
Funderburgh
J L
JL
Division of Biology, Kansas State University, Manhattan 66506.
Conrad
G W
GW
D000581:Amidohydrolases / Q000378:metabolism; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D011508:Chondroitin Sulfate Proteoglycans / Q000302:isolation & purification* / Q000378:metabolism; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003315:Cornea / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D006025:Glycosaminoglycans / Q000302:isolation & purification*; D006026:Glycoside Hydrolases; D006031:Glycosylation; D007632:Keratan Sulfate / Q000302:isolation & purification* / Q000378:metabolism; D000071234:Lumican; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010449:Peptide Mapping; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D011509:Proteoglycans / Q000302:isolation & purification*; D012697:Serine Endopeptidases / Q000378:metabolism; D014357:Trypsin; D001616:beta-Galactosidase / Q000378:metabolism
D000596:Amino Acids; D011508:Chondroitin Sulfate Proteoglycans; D006025:Glycosaminoglycans; D000071234:Lumican; D011509:Proteoglycans; D007632:Keratan Sulfate; D006026:Glycoside Hydrolases; C026093:keratan-sulfate endo-1,4-beta-galactosidase; D001616:beta-Galactosidase; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase