Vascular anticoagulant alpha (VAC alpha, annexin V) is a member of the family of calcium and phospholipid binding proteins, the annexins. The binding properties of VAC alpha to phospholipid bilayers were studied by ellipsometry. Adsorption was calcium-dependent and completely reversible upon calcium depletion. Half-maximal adsorptions to phospholipid bilayers consisting of 100, 20, 5, and 1% dioleoyl-phosphatidylserine (DOPS) supplemented with dioleoyl-phosphatidylcholine (DOPC) were reached at Ca2+ concentrations of 0.04, 0.22, 1.5, and 8.6 mM. These surfaces all showed the same maximal adsorption of 0.22 +/- 0.01 micrograms of VAC alpha/cm2 (mean +/- S.D.). The adsorption to bilayers containing more than 10% DOPS was independent of VAC alpha concentrations in the range of 0.5-100 nM. Dissociation constants for VAC alpha binding to these surfaces were estimated to be below 2 x 10(-10) M. No adsorption was observed on pure DOPC bilayers at a Ca2+ concentration of 3 mM. The ability to mediate VAC alpha binding to 20% DOPS/80% DOPC bilayers was highly specific for Ca2+. The use of other divalent cations resulted in decreased binding in the order Cd2+ greater than Zn2+ greater than Mn2+ greater than Co2+ greater than Ba2+ greater than Mg2+. Zinc ions had a synergistic effect on Ca2(+)-dependent VAC alpha binding. The Ca2+ concentration needed for half-maximal binding to cardiolipin, dioleoyl-phosphatidylglycerol, DOPS, phosphatidylinositol, phosphatidic acid, dioleoyl-phosphatidylethanolamine, and sphingomyelin increased in that order. Adsorption was independent of the overall surface charge of the phospholipid membrane.
Binding of vascular anticoagulant alpha (VAC alpha) to planar phospholipid bilayers.
H. Andree,C. Reutelingsperger,R. Hauptmann,H. Hemker,W. Hermens,G. Willems
Published 1990 in Journal of Biological Chemistry
ABSTRACT
PUBLICATION RECORD
- Publication year
1990
- Venue
Journal of Biological Chemistry
- Publication date
1990-03-25
- Fields of study
Medicine, Chemistry
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- calcium ions
Ca2+ ions used as the divalent cation required for VAC alpha binding in the experiments.
Aliases: Ca2+
- compared phospholipid species
The set of membrane lipids compared for calcium-dependent binding, including cardiolipin, phosphatidylglycerol, DOPS, phosphatidylinositol, phosphatidic acid, phosphatidylethanolamine, and sphingomyelin.
Aliases: tested phospholipids
- dioleoyl-phosphatidylcholine (dopc)
A phosphatidylcholine-containing membrane lipid used as the neutral bilayer component in the adsorption measurements.
Aliases: DOPC
- dioleoyl-phosphatidylserine (dops)
A phosphatidylserine-containing membrane lipid used to vary bilayer composition in the adsorption measurements.
Aliases: DOPS
- other divalent cations
Divalent metal ions other than calcium that were tested for their ability to support VAC alpha binding.
Aliases: divalent cations
- phospholipid bilayers
Planar membrane bilayers made from phospholipids and used as the binding surface in the assays.
Aliases: lipid bilayers, planar bilayers
- vac alpha
Vascular anticoagulant alpha, also called annexin V, is the calcium- and phospholipid-binding protein examined in the bilayer assays.
Aliases: annexin V
- zinc ions
Zn2+ ions tested both as alternative divalent cations and as a possible synergistic cofactor for calcium-dependent binding.
Aliases: Zn2+
REFERENCES
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