Ganglioside Partitioning and Aggregation in Phase-Separated Monolayers Characterized by Bodipy GM1 Monomer/Dimer Emission

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• 作者：Oana Coban ; Melanie Burger ; Mike Laliberte ; Anatoli Ianoul ; Linda J. Johnston
• 刊名：Langmuir
• 出版年：2007
• 出版时间：June 5, 2007
• 年：2007
• 卷：23
• 期：12
• 页码：6704 - 6711
• 全文大小：957K
• 年卷期：v.23,no.12(June 5, 2007)
• ISSN：1520-5827

文摘

The distribution of Bodipy GM1 in monolayers of binary and ternary lipid mixtures with coexisting fluid and orderedphases has been examined using a combination of atomic force microscopy and near-field scanning optical microscopy.Monolayers deposited at high (30 mN/m) and low (5 or 10 mN/m) surface pressures were examined and comparedto those containing the same concentration of unlabeled ganglioside. Measurements of monomer and dimer Bodipyemission were used to distinguish aggregated from dilute ganglioside levels. For binary DPPC/DOPC monolayers,Bodipy GM1 is distributed throughout both the fluid and ordered phases at low surface pressures, and both labeledand unlabeled gangliosides result in a reduction in the size of ordered DPPC domains at 0.4% and the appearanceof small aligned ganglioside-rich domains at 4%. In agreement with earlier studies, GM1 is heterogeneously distributedin small islands in the condensed DPPC domains at high surface pressure. By contrast, Bodipy GM1 causes thedisappearance of large DPPC domains at 0.4% and the formation of a new GM1-rich phase at 4%. The addition ofboth gangliosides leads to a comparable loss of large ordered domains at low surface pressure and the appearanceof a new GM1-rich phase at 30 mN/m for ternary lipid mixtures containing cholesterol. The results demonstrate thecomplexity of GM1 partitioning and illustrate the utility of complementary AFM and high spatial resolution two-colorfluorescence experiments for understanding Bodipy GM1 aggregation and distribution.