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 phos pholipid membranes to form a protective anti-thrombotic shield at the cell surface. The protein exhibits very high-affinity calcium-dependent interact ions with acidic phospholipid membranes, as well as specific binding to gly cosaminoglycans (GAGs) such as heparin and heparan sulfate, a major compone nt of cell surface proteoglycans. At present, there is no structural inform ation to elucidate this interaction or the role it may play in annexin V fu nction at the cell surface.