title: Cholesterol displacement by ceramide in sphingomyelin-containing liquid-ordered domains, and generation of gel regions in giant lipidic vesicles.
abstract: Fluorescence confocal microscopy and differential scanning calorimetry are used in combination to study the phase behaviour of bilayers composed of PC:PE:SM:Chol equimolecular mixtures, in the presence or absence of 10 mol% egg ceramide. In the absence of ceramide, separate liquid-ordered and liquid-disordered domains are observed in giant unilamellar vesicles. In the presence of ceramide, gel-like domains appear within the liquid-ordered regions. The melting properties of these gel-like domains resemble those of SM:ceramide binary mixtures, suggesting Chol displacement by ceramide from SM:Chol-rich liquid-ordered regions. Thus three kinds of domains coexist within a single vesicle in the presence of ceramide: gel, liquid-ordered, and liquid-disordered. In contrast, when 10 mol% egg diacylglycerol is added instead of ceramide, homogeneous vesicles, consisting only of liquid-disordered bilayers, are observed.
authors.affiliation: Unidad de Biofísica (Centro Mixto CSIC-UPV/EHU), Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Sot
authors.forename: Maitane
authors.initials: M
authors.lastname: Ibarguren
authors.forename: Jon V
authors.initials: JV
authors.lastname: Busto
authors.forename: L-Ruth
authors.initials: LR
authors.lastname: Montes
authors.forename: Félix M
authors.initials: FM
authors.lastname: Goñi
authors.forename: Alicia
authors.initials: A
authors.lastname: Alonso