Identification of link proteins and a 116,000-Dalton matrix protein in canine meniscus

The menisci are collagen-rich, fibrocartilagenous structures which are important in protecting the articular cartilage of the knee from some of the impact of weight-bearing. Meniscal proteoglycans have been studied in several mammalian species, including the dog, but very little is known about the noncollagenous proteins of the menisci. In the present study, 4 M guanidinium chloride extracts of meniscal cartilage from normal adult mongrel dogs were studied, and several noncollagenous proteins, including the link proteins and a 116,000-Da subunit protein, which we have recently described in articular cartilage, were found in meniscal cartilage. The 116,000-Da subunit protein represents 3.8% of the total protein extracted from meniscal cartilage. The link proteins sedimented in the bottom of an associative cesium chloride density gradient, where high-buoyant-density proteoglycans sediment.