Title :
The asparagine-linked oligosaccharides asparagine-linked oligosaccharides on
tissue factor pathway inhibitor terminate with
SO4-4GalNAc beta 1, 4GlcNAc beta 1,2 Mana alpha
Abstract :
- Tissue factor pathway inhibitor ( TFPI ) produced by endothelial cells contains sulfated Asn-linked oligosaccharides Asn-linked oligosaccharides
- We have determined that greater than 70% of the oligosaccharides on recombinant TFPI expressed in 293 cells terminate with the sequence SO4-4GalNAc beta 1, 4GlcNAc beta 1, 2Man alpha
- Oligosaccharides terminating with this sequence have previously been described on lutropin , thyrotropin , and pro-opiomelanocortin: glycoproteins synthesized in the anterior pituitary
- A GalNAc-transferase that recognizes the tripeptide motif Pro-Xaa-Arg/Lys 6-9 residues N-terminal to Asn glycosylation sites accounts for the specific addition of GalNAc to the oligosaccharide acceptor on these glycoproteins , whereas a GalNAc beta 1,4GlcNAc beta 1, 2Man alpha-4-sulfotransferase accounts for the addition of sulfate
- The sulfated oligosaccharides present on these hormones are responsible for their rapid clearance from plasma by a receptor in hepatic reticuloendothelial cells
- GalNAc- and sulfotransferase activities with the same properties as those expressed in the pituitary are detected at high levels in 293 cells and at lower levels in endothelial cells
- Chinese hamster ovary (CHO) cells do not contain detectable levels of either transferase and rTFPI expressed in CHO cells does not contain sulfated Asn-linked oligosaccharides Asn-linked oligosaccharides
- TFPI contains the sequence Pro-Phe-Lys, 9 residues N-terminal to the glycosylation site at position 228 ; this tripeptide may act as the recognition sequence for the GalNAc-transferase
- rTFPI produced by 293 cells, but not that produced by CHO cells, is bound by the receptor on hepatic reticuloendothelial cells suggesting the sulfated structures play a role in the biologic behavior of TFPI