Abstract
Cartilage fibrils contain collagen II as the major constituent, but the presence of additional components, minor collagens, and noncollagenous glycoproteins is thought to be crucial for modulating several fibril properties. We have examined the distribution of two fibril constituents-decorin and collagen IX-in samples of fibril fragments obtained after bovine cartilage homogenization. Decorin was preferentially associated with a population of thicker fibril fragments from adult articular cartilage, but was not present on the thinnest fibrils. The binding was specific for the gap regions of the fibrils, and depended on the decorin core protein. Collagen IX, by contrast, predominated in the population with the thinnest fibrils, and was scarce on wider fibrils. Double-labeling experiments demonstrated the coexistence of decorin and collagen IX in some fibrils of intermediate diameter, although most fibril fragments from adult cartilage were strongly positive for one component and lacked the other. Fibril fragments from fetal epiphyseal cartilage showed a different pattern, with decorin and collagen IX frequently colocalized on fragments of intermediate and large diameters. Hence, the presence of collagen IX was not exclusive for fibrils of small diameter. These results establish that articular cartilage fibrils are biochemically heterogeneous. Different populations of fibrils share collagen II, but have distinct compositions with respect to macromolecules defining their surface properties.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.