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beta(2)-Glycoprotein I can exist in 2 conformations: implications for our understanding of the antiphospholipid syndrome

Agar, Cetin; van Os, Gwendolyn M. A.; Mörgelin, Matthias LU ; Sprenger, Richard R.; Marquart, J. Arnoud; Urbanus, Rolf T.; Derksen, Ronald H. W. M.; Meijers, Joost C. M. and de Groot, Philip G. (2010) In Blood 116(8). p.1336-1343
Abstract
The antiphospholipid syndrome is defined by the presence of antiphospholipid antibodies in blood of patients with thrombosis or fetal loss. There is ample evidence that beta(2)-glycoprotein I (beta(2)GPI) is the major antigen for antiphospholipid antibodies. The autoantibodies recognize beta(2)GPI when bound to anionic surfaces and not in solution. We showed that beta(2)GPI can exist in at least 2 different conformations: a circular plasma conformation and an "activated" open conformation. We also showed that the closed, circular conformation is maintained by interaction between the first and fifth domain of beta(2)GPI. By changing pH and salt concentration, we were able to convert the conformation of beta(2)GPI from the closed to the open... (More)
The antiphospholipid syndrome is defined by the presence of antiphospholipid antibodies in blood of patients with thrombosis or fetal loss. There is ample evidence that beta(2)-glycoprotein I (beta(2)GPI) is the major antigen for antiphospholipid antibodies. The autoantibodies recognize beta(2)GPI when bound to anionic surfaces and not in solution. We showed that beta(2)GPI can exist in at least 2 different conformations: a circular plasma conformation and an "activated" open conformation. We also showed that the closed, circular conformation is maintained by interaction between the first and fifth domain of beta(2)GPI. By changing pH and salt concentration, we were able to convert the conformation of beta(2)GPI from the closed to the open conformation and back. In the activated open conformation, a cryptic epitope in the first domain becomes exposed that enables patient antibodies to bind and form an antibody-beta(2)GPI complex. We also demonstrate that the open conformation of beta(2)GPI prolonged the activated partial thromboplastin time when added to normal plasma, whereas the activated partial thromboplastin time is further prolonged by addition of anti-beta(2)GPI antibodies. The conformational change of beta(2)GPI, and the influence of the autoantibodies may have important consequences for our understanding of the antiphospholipid syndrome. (Blood. 2010; 116(8): 1336-1343) (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Blood
volume
116
issue
8
pages
1336 - 1343
publisher
American Society of Hematology
external identifiers
  • wos:000281354300023
  • scopus:77956488547
ISSN
1528-0020
DOI
10.1182/blood-2009-12-260976
language
English
LU publication?
yes
id
bbe17bea-48e0-49bb-81d6-2e381b4a32c4 (old id 1672461)
date added to LUP
2010-09-23 14:03:45
date last changed
2018-07-15 03:13:27
@article{bbe17bea-48e0-49bb-81d6-2e381b4a32c4,
  abstract     = {The antiphospholipid syndrome is defined by the presence of antiphospholipid antibodies in blood of patients with thrombosis or fetal loss. There is ample evidence that beta(2)-glycoprotein I (beta(2)GPI) is the major antigen for antiphospholipid antibodies. The autoantibodies recognize beta(2)GPI when bound to anionic surfaces and not in solution. We showed that beta(2)GPI can exist in at least 2 different conformations: a circular plasma conformation and an "activated" open conformation. We also showed that the closed, circular conformation is maintained by interaction between the first and fifth domain of beta(2)GPI. By changing pH and salt concentration, we were able to convert the conformation of beta(2)GPI from the closed to the open conformation and back. In the activated open conformation, a cryptic epitope in the first domain becomes exposed that enables patient antibodies to bind and form an antibody-beta(2)GPI complex. We also demonstrate that the open conformation of beta(2)GPI prolonged the activated partial thromboplastin time when added to normal plasma, whereas the activated partial thromboplastin time is further prolonged by addition of anti-beta(2)GPI antibodies. The conformational change of beta(2)GPI, and the influence of the autoantibodies may have important consequences for our understanding of the antiphospholipid syndrome. (Blood. 2010; 116(8): 1336-1343)},
  author       = {Agar, Cetin and van Os, Gwendolyn M. A. and Mörgelin, Matthias and Sprenger, Richard R. and Marquart, J. Arnoud and Urbanus, Rolf T. and Derksen, Ronald H. W. M. and Meijers, Joost C. M. and de Groot, Philip G.},
  issn         = {1528-0020},
  language     = {eng},
  number       = {8},
  pages        = {1336--1343},
  publisher    = {American Society of Hematology},
  series       = {Blood},
  title        = {beta(2)-Glycoprotein I can exist in 2 conformations: implications for our understanding of the antiphospholipid syndrome},
  url          = {http://dx.doi.org/10.1182/blood-2009-12-260976},
  volume       = {116},
  year         = {2010},
}