title: Domain formation and stability in complex lipid bilayers as reported by cholestatrienol.
abstract: In this study, we used cholestatrienol (CTL) as a fluorescent reporter molecule to study sterol-rich L(o) domains in complex lipid bilayers. CTL is a fluorescent cholesterol analog that mimics the behavior of cholesterol well. The ability of 12SLPC to quench the fluorescence of cholestatrienol gives a measure of the amount of sterol included in L(o) domains in mixed lipid membranes. The stability of sterol-rich domains formed in complex lipid mixtures containing saturated sphingomyelins, phosphatidylcholines, or galactosylceramide as potential domain-forming lipids were studied. The amount of sterol associated with sterol-rich domains seemed to always increase with increasing temperature. The quenching efficiency was highly dependent on the domain-forming lipid present in complex lipid mixtures. Sphingomyelins formed stable sterol-enriched domains and were able to shield CTL from quenching better than the other lipids included in this study. The saturated phosphatidylcholines also formed sterol-rich domains, but the quenching efficiency in membranes with these was higher than with sphingomyelins and the domains melted at lower temperatures. PGalCer was not able to form sterol-enriched domains. However, we found that PGalCer stabilized sterol-rich domains formed in PSM-containing bilayers. Using a fluorescent ceramide analog, we also demonstrated that N-palmitoyl-ceramide displaced the sterol from sphingolipid-rich domains in mixed bilayer membranes.
authors.affiliation: Department of Biochemistry and Pharmacy, Abo Akademi University, Turku, Finland.
authors.forename: Y Jenny E
authors.initials: YJ
authors.lastname: Björkqvist
authors.forename: Thomas K M
authors.initials: TK
authors.lastname: Nyholm
authors.forename: J Peter
authors.initials: JP
authors.lastname: Slotte
authors.forename: Bodil
authors.initials: B
authors.lastname: Ramstedt
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D002782:Cholestenes / Q000737:chemistry*; D004355:Drug Stability; D005456:Fluorescent Dyes / Q000737:chemistry; D005699:Galactosylceramides / Q000737:chemistry; D066298:In Vitro Techniques; D008051:Lipid Bilayers / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013816:Thermodynamics
chemical_list: D002782:Cholestenes; D005456:Fluorescent Dyes; D005699:Galactosylceramides; D008051:Lipid Bilayers; D010743:Phospholipids; C025498:cholesta-5,7,9-trien-3 beta-ol