The annexins are a family of Ca2+-regulated phospholipid binding proteins that are involved in membrane domain organization and membrane trafficking. Although they are widely studied and crystal structures are available for several soluble annexins their mode of membrane association has never been studied at the molecular level. Here we obtained molecular information on the annexin-membrane int...

The electrical conductivity of black phosphatidylserine membranes, in solutions of 100 mM NaCl, 10 mM sodium phosphate (pH 7.1), is strongly increased by the intrinsic proteins ("strongly bound" protein fraction) from human erythrocyte membranes. The magnitude of the conductivity increase is highly dependent on the maximum pH-value pH used during the preparation of the protein (8.0 less than or...

BACKGROUND Antibodies against cardiolipin and phosphatidylserine (anti-CL and anti-PS) are associated with thrombosis. In contrast, we determined that IgM antibodies against oxidized CL and PS (OxCL and OxPS) and phosphorylcholine (anti-PC) could be protection markers for cardiovascular disease (CVD). METHODS 226 individuals with established hypertension (diastolic pressure>95 mmHg) from the ...

Lipid-anchored Ras GTPases form transient, spatially segregated nanoclusters on the plasma membrane that are essential for high-fidelity signal transmission. The lipid composition of Ras nanoclusters, however, has not previously been investigated. High-resolution spatial mapping shows that different Ras nanoclusters have distinct lipid compositions, indicating that Ras proteins engage in isofor...

Annexins are abundant and ubiquitous proteins that bind, by their four structurally identical domain cores, to phosphatidylserine-containing membranes in the presence of Ca2+. Using molecular simulation and mutagenesis, we have identified a new phosphatidylserine-binding site in annexin V domain 1 and established its structure. The residues involved in this site constitute a consensus sequence ...

Distal neuronal terminals may be the site of apoptotic events and early synapse loss in neurodegenerative disease. To examine apoptosis in synaptic regions, we established a cell-free assay using a rat brain crude synaptosomal preparation (P-2 fraction) as a model system. The apoptosis marker annexin-V was used to measure phosphatidylserine (PS) exposure, and to ensure that only intact terminal...

Myoblast fusion is essential for the formation of skeletal muscle myofibres. Studies have shown that phosphatidylserine is necessary for myoblast fusion, but the underlying mechanism is not known. Here we show that the phosphatidylserine receptor stabilin-2 acts as a membrane protein for myoblast fusion during myogenic differentiation and muscle regeneration. Stabilin-2 expression is induced du...

Expression of phosphatidylserine (PS) on the surface of both macrophages and their apoptotic targets is required for efficient phagocytosis. Monocytes, the precursors of macrophages, do not express PS on their surface and do not efficiently phagocytose apoptotic cells. We report here that PS appears on the surface of both human monocytic U937 cells and primary human monocytes as they differenti...

Small unilamellar vesicles composed of phosphatidylserine (PS) and cholesterol at various ratios were employed in studying the effect of cholesterol on Ca2+-induced vesicle aggregation and fusion using the Tb/dipicolinic acid assay. The leakage of preencapsulated Tb3+ was also measured. The analysis of the data provided estimates for the rate of aggregation C11, and the rate of fusion per se, f...

A modification of the phospholipase D-catalyzed synthesis of phosphatidylserine is described, which allows the handling of small quantities of lipid without the need for an ether-water system. By using octylglucoside to disperse the lipid during the enzymatic conversion, it was possible to reduce the volume of the reaction mixture to 50-100 microliters. The amount of lipid that can be handled i...