Identification of the N-linked oligosaccharide sites in chick corneal lumican and keratocan that receive keratan sulfate.
J Biol Chem
; 273(16): 9615-21, 1998 Apr 17.
Article
en En
| MEDLINE
| ID: mdl-9545293
ABSTRACT
Corneal proteoglycans have chondroitin/dermatan and keratan sulfate (KS) chains and belong to the leucine-rich proteoglycan gene family. Corneal KS is N-linked to Asn of an NX(S/T) site through a complex oligosaccharide linkage region. Only some sites receive KS, whereas others remain in a high mannose form. To determine whether the attachment of KS was biased toward specific sites, we isolated trypsin-digested KS-containing fragments of chick corneal proteoglycans and sequenced the peptides. Results showed that all of the peptides sequenced aligned to the deduced amino acid sequence of either chick lumican or chick keratocan at the first, third, and fourth potential N-linked sites. Sites 1 and 4 in lumican and keratocan are in a homologous location. By analogy with the structure of ribonuclease inhibitor (a Leu-rich repeat containing protein), the KS chains would extend outward on the outer face of a horseshoe-like structure. The amino acid sequences surrounding the potential N-linked sites were also compared. Sites receiving KS tend to have a higher occurrence of aromatic residues, in particular Phe, located within 3 amino acids of NX(S/T). These conserved Phe residues may have a role in the conversion of high mannose N-linked oligosaccharides to polylactosamine and/or keratan sulfate.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Oligosacáridos
/
Proteoglicanos Tipo Condroitín Sulfato
/
Proteoglicanos
/
Córnea
/
Sulfato de Queratano
Tipo de estudio:
Diagnostic_studies
Límite:
Animals
Idioma:
En
Revista:
J Biol Chem
Año:
1998
Tipo del documento:
Article
País de afiliación:
Estados Unidos