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Cholesterol displacement by ceramide in sphingomyelin‐containing liquid‐ordered domains, and generation of gel regions in giant lipidic vesicles
Author(s) -
Sot Jesús,
Ibarguren Maitane,
Busto Jon V.,
Montes L.-Ruth,
Goñi Félix M.,
Alonso Alicia
Publication year - 2008
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2008.08.016
Subject(s) - sphingomyelin , ceramide , vesicle , chemistry , cholesterol , sphingolipid , displacement (psychology) , biophysics , biochemistry , membrane , biology , apoptosis , psychology , psychotherapist
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.