Metabolism of a cartilage matrix glycoprotein in normal and osteoarthritic canine articular cartilage

Open Access
Publisher Website
Google Scholar
Abstract
We have recently described a 550,000‐dalton noncollagenous cartilage matrix glycoprotein (CMGP), with subunits of 130,000, which is present in hyaline cartilage and fibrocartilage. Biosynthetic studies indicated that CMGP was synthesized by short‐term organ cultures of normal canine articular cartilage, representing approximately 9% of the total 3H‐leucine incorporated into protein in 24‐hour cultures. There was no incorporation of 35S‐sulfate or 3H‐mannose into CMGP under these conditions, but the protein did incorporate 32P‐phosphate. The majority of the 3H‐leucine‐labeled CMGP was removed after 24 hours of chase with unlabeled leucine, and only a small amount remained at 72 hours, which suggests that there was rapid metabolism of the protein. CMGP was not detected in cartilage after addition of cycloheximide to the culture medium; this confirms its short half‐life. Cultures of osteoarthritic cartilage obtained from dogs 8–10 weeks after anterior cruciate ligament transection revealed no difference in the metabolism of CMGP in this tissue compared with that found in cultures of normal articular cartilage.