Immature bovine cartilages and intervertebral-disc tissue all revealed a prominent protein, not present in the adult tissues, in non-denaturing extracts made with chondroitin ABC lyase (Ec 184.108.40.206), Streptomyces hyaluronidase (EC 220.127.116.11) or 1 M NaCl. The protein ran on SDS-polyacrylamide electrophoresis, before disulphide reduction, as a close doublet of bands of apparent molecular weight 110 000 and 105 000. After reduction, they dissociated respectively into two protein bands at 37 000 and 35 000, indicating that the initial molecules were disulphide-bounded trimers. Amino-terminal sequence analysis established the identity of both proteins (Mr 110 000 and Mr 105 000) as forms of the carboxypropeptide of type II collagen. The larger molecule appeared to be the trimer of intact α1(II) carboxypropeptides and the smaller, a version composed of chains that were ten residues shorter at their amino-terminal ends. The material appears to be identical to chondrocalcin, a protein previously found to be enriched in fetal growth plate and named on the basis that it may play a role in cartilage calcification. The present findings, however, indicate that the protein is equally abundant in all type II collagen-synthesizing young cartilages, including nucleus pulposus of the intervertebral disc and other cartilages that never calcify.
|Original language||English (US)|
|Number of pages||7|
|Journal||Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular|
|State||Published - Dec 18 1987|
All Science Journal Classification (ASJC) codes
- Structural Biology
- Molecular Biology