Identification of a high-molecular-weight (greater than 400 000) protein in hyaline cartilage

A high-molecular-weight (greater than 400 000) non-collagenous protein has been identified in normal articular cartilage from several mammalian species and in bovine tracheal cartilage. This protein is reduced by 2-mercaptoethanol to subunits with a molecular weight of 116 000, which appear to constitute approx. 2-4% of the total protein detectable by the Lowry assay in 4 M guanidinium chloride extracts of normal bovine and canine articular cartilage. Antiserum to the 116 kDa subunit protein from bovine articular cartilage cross-reacts with the intact and subunit proteins from bovine trachea and from normal canine, porcine and human articular cartilage. This protein is not found in non-cartilagenous tissues, suggesting that it is a cartilage-specific protein. We conclude that the greater than 400 kDa protein and its subunit are ubiquitous and quantitatively significant proteins in hyaline cartilage.