Annexin V-heparin oligosaccharide complex suggests heparan sulfate-mediated assembly on cell surfaces

Background: Annexin V, an abundant anticoagulant protein, has been proposed to exert its effects by self-assembling into highly ordered arrays on phospholipid membranes to form a protective anti-thrombotic shield at the cell surface. The protein exhibits very high-affinity calcium-dependent interactions with acidic phospholipid membranes, as well as specific binding to glycosaminoglycans (GAGs) such as heparin and heparan sulfate, a major component of cell surface proteoglycans. At present, there is no structural information to elucidate this interaction or the role it may play in annexin V function at the cell surface.