文献：Ultrafast Diffusion of a Fluorescent Cholesterol Analog in Compartmentalized Plasma Membranes

作者：Nao Hiramoto-Yamaki, Kenji A. K. Tanaka, Kenichi G. N. Suzuki, Koichiro M. Hirosawa, Manami S. H. Miyahara, Ziya Kalay, Koichiro Tanaka, Rinshi S. Kasai … See all authors 

文献链接：https://onlinelibrary.wiley.com/doi/full/10.1111/tra.12163

Cholesterol distribution and dynamics in the plasma membrane (PM) are poorly understood. The recent development of Bodipy488-conjugated cholesterol molecule (Bdp-Chol) allowed us to study cholesterol behavior in the PM, using single fluorescent-molecule imaging. Surprisingly, in the intact PM, Bdp-Chol diffused at the fastest rate ever found for any molecules in the PM, with a median diffusion coefficient (D) of 3.4 µm2/second, which was ∼10 times greater than that of non-raft phospholipid molecules (0.33 µm2/second), despite Bdp-Chol's probable association with raft domains. Furthermore, Bdp-Chol exhibited no sign of entrapment in time scales longer than 0.5 milliseconds. In the blebbed PM, where actin filaments were largely depleted, Bdp-Chol and Cy3-conjugated dioleoylphosphatidylethanolamine (Cy3-DOPE) diffused at comparable Ds (medians = 5.8 and 6.2 µm2/second, respectively), indicating that the actin-based membrane skeleton reduces the D of Bdp-Chol only by a factor of ∼2 from that in the blebbed PM, whereas it reduces the D of Cy3-DOPE by a factor of ∼20. These results are consistent with the previously proposed model, in which the PM is compartmentalized by the actin-based membrane-skeleton fence and its associated transmembrane picket proteins for the macroscopic diffusion of all of the membrane molecules, and suggest that the probability of Bdp-Chol passing through the compartment boundaries, once it enters the boundary, is ∼10× greater than that of Cy3-DOPE. Since the compartment sizes are greater than those of the putative raft domains, we conclude that raft domains coexist with membrane-skeleton-induced compartments and are contained within them.

Bodipy488共轭胆固醇分子（Bdp-Chol）的发展使我们能够使用单荧光分子成像研究PM中的胆固醇行为。

中值扩散系数（D）为3.4µm2/秒，比非筏磷脂分子（0.33µm2/秒钟）大10倍，尽管Bdp-Chul可能与筏结构域有关。此外，Bdp-Chol在超过0.5的时间尺度上没有表现出被困的迹象 毫秒。

在泡状PM中，肌动蛋白丝大量耗尽，Bdp-Chol和Cy3结合的二油酰基磷脂酰乙醇胺（Cy3-DOPE）以相当的Ds（中位数）扩散 = 5.8 和6.2µm2/秒），表明基于肌动蛋白的膜骨架仅将Bdp-Chol的D降低了泡状PM的约2倍，而将Cy3-DOPE的D降低约20倍。

这些结果与之前提出的模型一致，在该模型中，PM被基于肌动蛋白的膜骨架栅栏及其相关的跨膜尖桩蛋白分隔，用于所有膜分子的宏观扩散，并表明Bdp-Chol一旦进入边界，通过隔室边界的概率比Cy3-DOPE大约10倍。由于隔室尺寸大于假定的筏域，我们得出结论，筏域与膜骨架诱导的隔室共存，并包含在其中。

相关推荐：

Cy3-DOPE

Cy3-DPPE

Cy3-DSPE

Cy3-PEG-DOPE

Cy3-PEG-DPPE

Cy5-DOPE

Cy5-DPPE

Cy5-DSPE

Cy5-PEG-DOPE

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