Rand Figure 6
Rand Figure 6. (in Warkentin et al). Structure of human plasma β2GPI. / (A) Ribbon model of β2GPI based upon crystal structure: the protein is composed of an extended chain of 5 SCR domains having a “fishhook” appearance. The structure of SCR domain V deviates from the standard fold of the 4 other domains and forms the putative phospholipid-binding site. β-strands are shown in red and helices in green. / (B) The structural data suggest a simple membrane-binding mechanism in which the cationic patch of domain V has an affinity for anionic phospholipid. The stretch of Ser311 to Lys317 forms a hydrophobic loop that inserts into the lipid bilayer and positions Trp316 at the interface region between the acyl chains and the phosphate headgroups of the lipids, thereby anchoring the β2GPI in the membrane. / Current data support the hypothesis that aPL antibodies reactive against β2GPI mainly recognize epitopes on domains I and II and that antibody-mediated dimerization of β2GPI markedly increases the affinity of β2GPI for phospholipid. / Reprinted with permission from Bouma B, de Groot PG, van den Elsen JM, et al. Adhesion mechanism of human beta(2)-glycoprotein I to phospholipids based on its crystal structure. EMBO J. 1999;18:5166–5174. / Abbreviations: aPL, antiphospholipid; β2GPI, β2-glycoprotein I; SCR, short consensus repeat.

(in Warkentin et al). Structure of human plasma β2GPI.

(A) Ribbon model of β2GPI based upon crystal structure: the protein is composed of an extended chain of 5 SCR domains having a “fishhook” appearance. The structure of SCR domain V deviates from the standard fold of the 4 other domains and forms the putative phospholipid-binding site. β-strands are shown in red and helices in green.

(B) The structural data suggest a simple membrane-binding mechanism in which the cationic patch of domain V has an affinity for anionic phospholipid. The stretch of Ser311 to Lys317 forms a hydrophobic loop that inserts into the lipid bilayer and positions Trp316 at the interface region between the acyl chains and the phosphate headgroups of the lipids, thereby anchoring the β2GPI in the membrane.

Current data support the hypothesis that aPL antibodies reactive against β2GPI mainly recognize epitopes on domains I and II and that antibody-mediated dimerization of β2GPI markedly increases the affinity of β2GPI for phospholipid.

Reprinted with permission from

Bouma B, de Groot PG, van den Elsen JM, et al. Adhesion mechanism of human beta(2)-glycoprotein I to phospholipids based on its crystal structure. EMBO J.1999;18:5166–5174.

Abbreviations: aPL, antiphospholipid; β2GPI, β2-glycoprotein I; SCR, short consensus repeat.

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