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Behaviour of bovine phosphatidylethanolamineâbinding protein with model membranes.â: Evidence of affinity for negatively charged membranes
- VallÃ©e, BÃ©atrice S., Tauc, Patrick, Brochon, JeanâClaude, MagetâDana, RÃ©gine, LeliÃ¨vre, Dominique, MetzâBoutigue, MarieâHÃ©lÃ¨ne, Bureaud, Nicole, Schoentgen, FranÃ§oise
- European journal of biochemistry 2001 v.268 no.22 pp. 5831-5841
- binding sites, cattle, cholesterol, electrostatic interactions, peptides, phosphatidylethanolamines, solubilization
- The ability of phosphatidylethanolamineâbinding protein (PEBP) to bind membranes was tested by using small and large unilamellar vesicles and monolayers composed of lâÎ±â1,2âdimyristoylphosphatidylcholine, lâÎ±â1,2âdimyristoylphosphatidylglycerol and lâÎ±â1,2âdimyristoylphosphatidylethanolamine. PEBP only bound to model membranes containing lâÎ±â1,2âdimyristoylphosphatidylglycerol; the interaction was primarily due to electrostatic forces between the basic protein and the acidic phospholipids. Further experiments indicated that the interaction was not dependent on the length and unsaturation of the phospholipid acyl chains and was not modified by the presence of cholesterol in the membrane. PEBP affinity for negatively charged membranes is puzzling considering the previous identification of the protein as a phosphatidylethanolamineâbinding protein, and suggests that the association of PEBP with phospholipid membranes is driven by a mechanism other than its binding to solubilized phosphatidylethanolamine. An explanation was suggested by its threeâdimensional structure: a small cavity at the protein surface has been reported to be the binding site of the polar head of phosphatidylethanolamine, while the Nâterminal and Câterminal parts of PEBP, exposed at the protein surface, appear to be involved in the interaction with membranes. To test this hypothesis, we synthesized the two PEBP terminal regions and tested them with model membranes in parallel with the whole protein. Both peptides displayed the same behaviour as whole PEBP, indicating that they could participate in the binding of PEBP to membranes. Our results strongly suggest that PEBP directly interacts with negatively charged membrane microdomains in living cells.