Glycophorin-induced cholesterol-phospholipid domains in dimyristoylphosphatidylcholine bilayer vesicles.
Glycophorin has been incorporated into unilamellar cholesterol-containing dimyristoylphosphatidylcholine vesicles that were reconstituted by the freeze and thaw technique. Evidence was obtained for a protein-induced structural reorganization of these mixed membranes. By differential scanning calorimetry, we were able to construct a phase diagram for the phospholipid/cholesterol mixture consisting of a liquid-ordered, a solid-ordered, and a liquid-disordered phase. Glycophorin at low molar fractions (XG less than 3 X 10(-3)) increases the relative amount of lipid in the liquid-ordered phase, which is interpreted as an enrichment of cholesterol in the vicinity of the protein. The formation of such steroid-enriched domains could be demonstrated directly by electron paramagnetic resonance using a spin-labeled cholesterol analogue. A drastic increase of the spin-spin interaction of the labeled steroid was observed in the presence of glycophorin.
Tampé
R
R
Institute of Biochemistry, Technical University Darmstadt, FRG.
von Lukas
A
A
Galla
H J
HJ
D002152:Calorimetry, Differential Scanning / Q000379:methods; D002784:Cholesterol / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005615:Freezing; D006021:Glycophorins / Q000737:chemistry*; D008051:Lipid Bilayers; D008968:Molecular Conformation; D010446:Peptide Fragments; D013113:Spin Labels; D014357:Trypsin
D006021:Glycophorins; D008051:Lipid Bilayers; D010446:Peptide Fragments; D013113:Spin Labels; D002784:Cholesterol; D014357:Trypsin; D004134:Dimyristoylphosphatidylcholine