MATRIX PROTEINS BOUND TO ASSOCIATIVELY PREPARED PROTEOGLYCANS FROM BOVINE CARTILAGE

Proteoglycans were extracted from bovine tracheal cartilage by high-speed homogenization, the use of dissociative solvents being avoided. The homogenate was fractionated by gel chromatography, sucrose-density-gradient centrifugation and ion-exchange chromatography. A previously unrecognized protein, cartilage matrix protein, was identified by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. It cofractionated with the proteoglycans in all systems, indicating an interaction. The cartilage matrix protein-proteoglycan complex was dissociated by treatment with 4 M guanidinium chloride. The complex again formed when the guanidine was removed. The cartilage matrix protein has MW of more than 200,000. On reduction it yields subunits with MW of approximately 60,000.