Title : O-fucosylation is required for
ADAMTS13 secretion
Abstract :
- ADAMTS13 is a plasma metalloproteinase that cleaves von Willebrand factor to smaller, less thrombogenic forms
- Deficiency of ADAMTS13 activity in plasma leads to thrombotic thrombocytopenic purpura
- ADAMTS13 contains eight thrombospondin type 1 repeats (TSR), seven of which contain a consensus sequence for the direct addition of fucose to the hydroxyl group of serine or threonine
- Mass spectral analysis of tryptic peptides derived from human ADAMTS13 indicate that at least six of the TSRs are modified with an O-fucose disaccharide
- Analysis of [(3)H]fucose metabolically incorporated into ADAMTS13 demonstrated that the disaccharide has the structure glucose-beta1,3-fucose
- Mutation of the modified serine to alanine in TSR2 , TSR5, TSR7, and TSR8 reduced the secretion of ADAMTS13
- Mutation of more than one site dramatically reduced secretion regardless of the sites mutated
- When the expression of protein O-fucosyltransferase 2 ( POFUT2 ), the enzyme that transfers fucose to serines in TSRs, was reduced using siRNA, the secretion of ADAMTS13 decreased
- A similar outcome was observed when ADAMTS13 was expressed in a cell line unable to synthesize the donor for fucose addition, GDP-fucose
- Although overexpression of POFUT2 did not affect the secretion of wild-type ADAMTS13 , it did increase the secretion of the ADAMTS13 TSR1,2 double mutant but not that of ADAMTS13 TSR1-8 mutant
- Together these findings indicate that O-fucosylation is functionally significant for secretion of ADAMTS13
Output (sent_index, trigger,
protein,
sugar,
site):
- 0. O-fucosylation, , ADAMTS13, -, -
- 3. contains, , ADAMTS13, eight thrombospondin type 1 repeats, -
Output(Part-Of) (sent_index,
protein,
site):
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):