Vitreous contains a cartilage-related protein

The vitreous is a clear, gel-like mass in the posterior cavity of the eye. Its major components are type II collagen, hyaluronic acid, and water. A small amount of proteoglycan is also present. All of these molecules are found in cartilage as well. We have now identified a non-collagenous protein in bovine and human vitreous samples which has hitherto been found only in hyaline cartilage and fibrocartilage. This protein has a molecular weight of 550,000 and subunits of 130,000 MW and appears to be a shared cartilage and eye antigen. Its role, if any, in ocular disease associated with rheumatic disorders remains to be determined.