Visualizing Association of N-Ras in Lipid Microdomains: Influence of Domain Structure and Interfacial Adsorption
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- 作者：Chiara Nicolini ; Jö ; rg Baranski ; Stefanie Schlummer ; José ; Palomo ; Maria Lumbierres-Burgues ; Martin Kahms ; Jü ; rgen Kuhlmann ; Susana Sanchez ; Enrico Gratton ; Herbert Waldmann ; and Roland
- 刊名：Journal of the American Chemical Society
- 出版年：2006
- 出版时间：January 11, 2006
- 年：2006
- 卷：128
- 期：1
- 页码：192 - 201
- 全文大小：972K
- 年卷期：v.128,no.1(January 11, 2006)
- ISSN：1520-5126
文摘
In this study, two-photon fluorescence microscopy on giant unilamellar vesicles and tapping-mode atomic force microscopy (AFM) are applied to follow the insertion of a fluorescently (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, BODIPY) labeled and completely lipidated (hexadecylated and farnesylated)N-Ras protein into heterogeneous lipid bilayer systems. The bilayers consist of the canonical raft mixture1-palmitoyl-2-oleoylphosphatidylcholine (POPC), sphingomyelin, and cholesterol, which-depending on theconcentration of the constituents-separates into liquid-disordered (ld), liquid-ordered (lo), and solid-ordered(so) phases. The results provide direct evidence that partitioning of N-Ras occurs preferentially into liquid-disordered lipid domains, which is also reflected in a faster kinetics of incorporation into the fluid lipid bilayers.The phase sequence of preferential binding of N-Ras to mixed-domain lipid vesicles is ld > lo 
so.Intriguingly, we detect, using the better spatial resolution of AFM, also a large proportion of the lipidatedprotein located at the ld/lo phase boundary, thus leading to a favorable decrease in line tension that isassociated with the rim of the demixed phases. Such an interfacial adsorption effect may serve as analternative vehicle for association processes of signaling proteins in membranes.
so.Intriguingly, we detect, using the better spatial resolution of AFM, also a large proportion of the lipidatedprotein located at the ld/lo phase boundary, thus leading to a favorable decrease in line tension that isassociated with the rim of the demixed phases. Such an interfacial adsorption effect may serve as analternative vehicle for association processes of signaling proteins in membranes.