title: Cartilage type IX collagen is cross-linked by hydroxypyridinium residues.
abstract: Type IX collagen, a recently discovered, unusual protein of cartilage, has a segmented triple-helical structure containing interchain disulfides. Its polymeric form and function are unknown. When prepared by pepsin from bovine articular cartilage, type IX collagen was found to contain a high concentration of hydroxypyridinium cross-links, similar to that in type II collagen. Fluorescence spectroscopy located the hydroxylysyl pyridinoline and lysyl pyridinoline cross-linking residues exclusively in the high-molecular-weight collagen fraction, from which they were recovered predominantly in a single CNBr-derived peptide. The results point to a structural role for type IX collagen in cartilage matrix, possibly as an adhesion material to type II collagen fibrils.
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000032:analysis*; D002417:Cattle; D003094:Collagen / Q000302:isolation & purification*; D003488:Cyanogen Bromide; D004591:Electrophoresis, Polyacrylamide Gel; D005269:Femur; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000032:analysis; D011725:Pyridines / Q000032:analysis*; D013050:Spectrometry, Fluorescence
chemical_list: D046911:Macromolecular Substances; D010446:Peptide Fragments; D011725:Pyridines; C023500:3-hydroxypyridine; D003094:Collagen; D003488:Cyanogen Bromide