Crystal structure of human beta2-glycoprotein I: implications for phospholipid binding and the antiphospholipid syndrome.Schwarzenbacher, R., Zeth, K., Diederichs, K., Gries, A., Kostner, G.M., Laggner, P., Prassl, R.
(1999) EMBO J. 18: 6228-6239
- PubMed: 10562535
- DOI: 10.1093/emboj/18.22.6228
- PubMed Abstract:
- Crystallization and preliminary X-ray crystallographic studies on apolipoprotein H (beta-2-glycoprotein-I)
Saxena, A.,Gries, A.,Schwarzenbacher, R.,Kostner, G.M.,Laggner, P.,Prassl, R.
(1998) Acta Crystallogr.,Sect.D 54: 1450
The high affinity of human plasma beta2-glycoprotein I (beta(2)GPI), also known as apolipoprotein-H (ApoH), for negatively charged phospholipids determines its implication in a variety of physiological pathways, including blood coagulation and the im ...
The high affinity of human plasma beta2-glycoprotein I (beta(2)GPI), also known as apolipoprotein-H (ApoH), for negatively charged phospholipids determines its implication in a variety of physiological pathways, including blood coagulation and the immune response. beta(2)GPI is considered to be a cofactor for the binding of serum autoantibodies from antiphospholipid syndrome (APS) and correlated with thrombosis, lupus erythematosus and recurrent fetal loss. We solved the beta(2)GPI structure from a crystal form with 84% solvent and present a model containing all 326 amino acid residues and four glycans. The structure reveals four complement control protein modules and a distinctly folding fifth C-terminal domain arranged like beads on a string to form an elongated J-shaped molecule. Domain V folds into a central beta-spiral of four antiparallel beta-sheets with two small helices and an extended C-terminal loop region. It carries a distinct positive charge and the sequence motif CKNKEKKC close to the hydrophobic loop composed of residues LAFW (313-316), resulting in an excellent counterpart for interactions with negatively charged amphiphilic substances. The beta(2)GPI structure reveals potential autoantibody-binding sites and supports mutagenesis studies where Trp316 and CKNKEKKC have been found to be essential for the phospholipid-binding capacity of beta(2)GPI.
Institute of Biophysics and X-ray Structure Research, Austrian Academy of Sciences, Steyrergasse 17/6, A-8020 Graz.