查看文章

Human β 2‐glycoprotein I is a heavily glycosylated five‐domain plasma membrane‐adhesion protein, which has been implicated in blood coagulation and clearance of apoptotic bodies from the circulation. It is also the key antigen in the autoimmune disease anti‐phospholipid syndrome. The crystal structure of β 2‐glycoprotein I isolated from human plasma reveals an elongated fish‐hook‐like arrangement of the globular short consensus repeat domains. Half of the C‐terminal fifth domain deviates strongly from the standard fold, as observed in domains one to four. This aberrant half forms a specific phospholipid‐binding site. A large patch of 14 positively charged residues provides electrostatic interactions with anionic phospholipid headgroups and an exposed membrane‐insertion loop yields specificity for lipid layers. The observed spatial arrangement of the five domains suggests a functional partitioning of …