|
|||||||||
|
|
|
|
|
|
|
|
|
|
|
Blood, Vol. 94 No. 4 (August 15), 1999:
pp. 1337-1347
From the Departments of Pathology and Molecular Medicine, Laboratory
Medicine, and Medicine, McMaster University, Hamilton, Ontario,
Canada; the Hamilton Health Sciences Corp, Hamilton,
Ontario, Canada; and INSERM U474, Hôpital Henri Mondor,
Créteil, France.
Multimerin is a massive, soluble, homomultimeric, factor V-binding
protein found in platelet This article has been cited by other articles:
| |||||||||||
 |
 |
 |
|||||||
 |
 |
 |
 |
 |
 |
 |
 |
||
| Copyright © 1999 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
-granules and in vascular endothelium. Unlike platelets, endothelial cells contain multimerin within granules
that lack the secretory granule membrane protein P-selectin, and in
culture, they constitutively secrete most of their synthesized multimerin. To further evaluate multimerin's posttranslational processing and storage, we expressed human endothelial cell
prepromultimerin in a variety of cell lines, with and without pathways
for regulated secretion. The recombinant multimerin produced by these
different cells showed variations in its glycosylation, proteolytic
processing, and multimer profile, and human embryonic kidney 293 cells
recapitulated multimerin's normal processing for constitutive
secretion by human endothelial cells. When multimerin was expressed in
a neuroendocrine cell line capable of regulated protein secretion, it
was efficiently targeted for regulated secretion. However, the
multimerin stored in these cells was proteolyzed more extensively than
normally occurs in platelets, suggesting that endoproteases similar to those expressed by megakaryocytes are required to produce platelet-type multimerin. The impact of the tissue-specific differences in
multimerin's posttranslational processing on its functions is not yet
known. Multimerin's sorting and targeting for regulated secretion may be important for its functions and its association with factor V in
secretion granules.
