Release of heparan sulfate glycosaminoglycans from proteoglycans in Chinese hamster ovary cells does not require proteolysis of the core protein.

摘要: The initial steps in the catabolism of cell-associated heparan sulfate proteolgycans Chinese hamster ovary (CHO) cells are similar to what has been observed other cells, cell surface proteoglycans internalized and glycosaminoglycans released from core proteins cleaved small chains by intracellular heparanases. mechanism release cleavage reactions is unclear, since only intact small, pulse-chase experiments; however, it thought that precedes heparanas (Yanagishita, M., Hascall, V. C. (1992) J. Biol. Chem. 267, 9451-9454). relationship between these two were examined with proteoglycan synthesis mutant pgsE-606 (Bame, K. J., Esko, D. (1989) 264, 8059-8065), undersulfated synthesized a poor substrate for In addition chains, large glycosaminoglycan intermediate present suggesting as which subsequently catabolic acted upon heparanases, smaller than size found on proteoglycans, raising possibility first an endoglycosidic chain before proteolysis protein. To examine whether protein required chain, immobilized Sepharose incubated CHO extracts presence protease inhibitors. Heparan heparanases extract, indicating not prerequisite chain. addition, studies indicate there heparanase activity can recognize cleave sequences sulfate, but unable completely glycosaminoglycan, may be multiple activities responsible degrading chains.