Constituent proteoglycans of the human yellow ligament extracellular matrix

Abstract

    Three types of proteoglycans (PG-I, II and III) present in the human yellow ligament extracellular matrix were separated using a combination of CsCl isopycnic density gradient centrifugation, DEAE-Sephacel ion-exchange chromatography, gel-filtration on Sepharose CL-4B and CL-2B, and Octyl-Sepharose CL-4B chromatography. Proteoglycan-I was a high-molecular-weight proteoglycan, which was excluded by Sepharose CL-4B, and its molecular weight, estimated using sodium dedecyl sulfate-polyacrylamide gel electrophoresis, was over 350,000. The glycosaminoglycan chain of PG-I was composed of chondroitin 6-sulfate, and PG-I appeared to be an aggrecan-type proteoglycan. Proteoglycan-II and III were low-molecular-weight proteoglycans with molecular weights of 190,000 and 105,000, respectively. The core protein sizes of PG-II and III were similar, 44,000, but anti-human decorin antibody reacted with PG-III, not with PG-II. The glycosaminoglycan chain of PG-II contained dermatan sulfate and chondroitin 6-sulfate, whereas that of PG-III contained the former only. In the light of these results, PG-II and III were suggested to be biglycan- and decorin-type proteoglycans, respectively. The major proteoglycan in the human yellow ligament extracellular matrix was PG-III.