Immunohistochemical and biochemical evidence that the cartilage from cmd/cmd mice, who have an autosomal recessive lethal mutation causing cartilage matrix deficiency, synthesizes link protein nearly at a normal level is provided. Since cartilage-characteristic proteoglycan is not synthesized in this mutant mouse (K. Kimata, H-J. Barrach, K. S. Brown, and J. P. Pennypacker (1981) J. Biol. Chem. 256, 6961-6968), link proteins are apparently not in conventional proteoglycan aggregate. However, the link proteins are functional and able to interact with exogenous cartilage-characteristic proteoglycan monomer and hyaluronic acid to form aggregates.