- Paper Report
- Open Access
Chondroadherin binds to type II collagen
- Lillian Shum1
© Biomed Central Ltd 2001
- Received: 8 November 2001
- Accepted: 8 November 2001
- Published: 8 November 2001
- Articular cartilage
- binding assay
- protein extraction
- type II collagen
Chondroadherin belongs to a family of small leucine-rich repeat (LRR) proteoglycans that is a major component of the cartilage matrix. This family also includes biglycan, decorin, fibromodulin, and lumican. Type II collagen (CII) is the major collagenous component in cartilage; previous studies have demonstrated binding of CII with several LRR proteins, as well as to cartilage oligomeric matrix protein. This study tested the hypothesis that chondroadherin binds to CII.
Chondroadherin was 36 kDa in monomeric form, and 67 kDa in dimeric form. CII and chondroadherin were found to co-fractionate and were detected in tightly associated complexes. Chondroadherin was bound to specific sites on the collagen fibrils, at 185 nm and 267 nm from the C-terminal end of the collagen. These associations were similar in both extracted complexes from in vivo materials, and in reconstituted complexes from pure proteins. The equilibrium dissociation constant for this interaction was 40 nM.
Molecular cloning, sequencing, expression of recombinant chondroadherin, generation of antibodies, biochemical extraction and purification, ion exchange chromatography, zonal rate centrifugation in glycerol gradients, SDS-PAGE, western blotting, transmission electron microscopy, surface plasmon resonance
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