Radioimmunoassay of the 148-kilodalton cartilage protein. Distribution of the protein among bovine tissues.

A sensitive and specific radioimmunoassay for the 148 kDa cartilage protein (previously referred to as 'cartilage matrix protein') was developed. The protein is insoluble in conventional buffers and was therefore dissolved in sodium dodecyl sulphate. Excess sodium dodecyl sulphate was bound in mixed micelles with Triton X-100 before assay. Antibodies raised against the 148 kDa cartilage protein did not react with other cartilage macromolecules. Neither did they react with guanidinium chloride extracts of a number of non-cartilaginous tissues. The protein, then, is unique for cartilage. It was demonstrated in tracheal, nasal-septum, xiphisternal, auricular and epiphysial cartilage. Surprisingly, the protein was detected neither in extracts of articular cartilage nor in extracts of the anulus fibrosus or the nucleus pulposus of the intervertebral disc.