title: Aggregated proteoglycan synthesis in organ cultures of human nucleus pulposus.
abstract: Proteoglycans isolated under associative conditions in the presence of protease inhibitors from human nucleus pulposus contained 17% aggregate and 83% non-aggregating monomer (Kav = 0.5 on Sepharose CL-2B). Isolated aggregate after reduction and alkylation was resolved into two components (Kav = 0.15 and 0.43) on Sepharose CL-2B. Labeled proteoglycans isolated from parallel samples pulsed with [35S]sulfate and chased for up to 18 h were present largely as aggregated material (up to 78%). Reduction and alkylation of the labeled samples gave a labeled proteoglycan monomer with Kav = 0.15. Both the labeled and unlabeled chondroitin sulfate chains had the same distribution on Sepharose CL-6B and equivalent molecular weights (Mr = 2.0 x 10(3)). After chondroitinase ABC digestion, the unlabeled keratan sulfate-protein core was polydisperse with a Kav = 0.38 on Sepharose CL-4B while the labeled keratan sulfate-protein core had a Kav = 0.05. This indicates that the newly synthesized proteoglycan had a large core protein and suggests that the proteoglycans present in nucleus pulposus are originally synthesized as large molecular weight, aggregating proteoglycans.
mesh_terms: D006801:Humans; D007403:Intervertebral Disc / Q000378:metabolism*; D046911:Macromolecular Substances; D009924:Organ Culture Techniques; D011509:Proteoglycans / Q000096:biosynthesis* / Q000302:isolation & purification; D013431:Sulfates / Q000378:metabolism
chemical_list: D046911:Macromolecular Substances; D011509:Proteoglycans; D013431:Sulfates