a raft-associated species of phosphatidylethanolamine interacts with cholesterol comparably to sphingomyelin. a langmuir-blodgett monolayer study一种raft-associated磷脂酰乙醇胺鞘磷脂与胆固醇相对。.pdfVIP

A Raft-Associated Species of Phosphatidylethanolamine Interacts with Cholesterol Comparably to Sphingomyelin. A Langmuir-Blodgett Monolayer Study Michal Grzybek1¤a, Jakub Kubiak 1¤b, Agnieszka Łach 1, Magdalena Przybyło2, Aleksander F. Sikorski 1,2* 1 Laboratory of Cytobiochemistry, Biotechnology Faculty, University of Wrocław, Wroclaw, Poland, 2 Academic Centre for Biotechnology of Lipid Aggregates, Wroclaw, Poland Abstract Background: Specific interactions between sphingomyelin (SM) and cholesterol (Ch) are commonly believed to play a key role in the formation of rafts in the biological membranes. A weakness of this model is the implication that these microdomains are confined to the outer bilayer leaflet. The cytoplasmic leaflet, which contains the bulk of phosphatidylethanolamine (PE), phosphatidylserine (PS) and phosphatidylinositol (PI), is thought also to harbour half of the membrane cholesterol. Moreover, SLPE (1-stearoyl-2-linoleoyl-sn-glycero-3-phosphatidyl-ethanolamine) has recently been shown to be enriched in isolated detergent-resistant membranes (DRM), and this enrichment was independent of the method of isolation of DRM. Methodology/Principal Findings: Here we present quantitative evidence coming from Langmuir-Blodgett monolayer experiments that SLPE forms complex with Ch similar to that between SM and Ch. The energies of these interactions as calculated form the monolayer studies are highly negative. FRAP analysis showed that NBD-Ch recovery was similar in liposomes composed of DOPC/Ch SM or SLPE but not DPPE, providing further evidence that SLPE may form an lo phase in