Paul Comfurius

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The plasma membrane, which forms the physical barrier between the intra- and extracellular milieu, plays a pivotal role in the communication of cells with their environment. Exchanging metabolites, transferring signals and providing a platform for the assembly of multi-protein complexes are a few of the major functions of the plasma membrane, each of which(More)
The asymmetric phospholipid distribution in plasma membranes is normally maintained by energy-dependent lipid transporters that translocate different phospholipids from one monolayer to the other against their respective concentration gradients. When cells are activated, or enter apoptosis, lipid asymmetry can be perturbed by other lipid transporters(More)
The binding of affinity-purified anticardiolipin antibodies (ACA) to liposomes that contained cardiolipin or phosphatidylserine was investigated. ACA bound to these liposomes only in the presence of plasma or serum, which indicated a requirement for a plasma component. This component--referred to as aca-cofactor--was purified; its activity to support ACA(More)
In erythrocytes and platelets, activation of a nonspecific lipid flipsite termed the scramblase allows rapid, bidirectional transbilayer movement of all types of phospholipids. When applied to lymphoid cells, scramblase assays reveal a similar activity, with scrambling rates intermediate between those seen in platelets and erythrocytes. Scrambling activity(More)
Phosphatidylserine has been prepared from phosphatidylcholine by a one-step transphosphatidylation catalyzed by phospholipase D in the presence of L-serine. The resulting mixture of phosphatidylserine and phosphatidic acid is easily and rapidly separated by CM-cellulose column chromatography using step=wise elution with solvents containing increasing(More)
It has long been appreciated that lipids, particularly anionic phospholipids, promote blood coagulation. The last two decades have seen an increasing insight into the kinetic and mechanistic aspects regarding the mode of action of phospholipids in blood coagulation. This essay attempts to review these developments with particular emphasis on the structure(More)
beta 2-Glycoprotein I (beta 2GPI) is an essential cofactor for the binding to lipids of anticardiolipin antibodies (ACA), isolated from patients with anti-phospholipid syndrome. We used ellipsometry to study the binding of beta 2GPI and the beta 2GPI-mediated binding of ACA to planar membranes composed of phosphatidylcholine (PC) and 5-20 mol %(More)
Dithionite reduction of fluorescent (NBD) phospholipids was used as the basis of a continuous assay of transbilayer lipid movement to the cell surface during platelet activation. This assay reveals that virtually all previously internalized phosphatidylserine passes through the external leaflet of the membrane within 90 s after activation with Ca2+ and(More)