文獻：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 

文獻鏈接：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 ?m2/second, which was ～10 times greater than that of non-raft phospholipid molecules (0.33??m2/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 ?m2/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共軛膽固醇分子（Bdp-Chol）的發(fā)展使我們能夠使用單熒光分子成像研究PM中的膽固醇行為。

中值擴散系數(shù)（D）為3.4?m2/秒，比非筏磷脂分子（0.33?m2/秒鐘）大10倍，盡管Bdp-Chul可能與筏結(jié)構(gòu)域有關(guān)。此外，Bdp-Chol在超過0.5的時間尺度上沒有表現(xiàn)出被困的跡象?毫秒。

在泡狀PM中，肌動蛋白絲大量耗盡，Bdp-Chol和Cy3結(jié)合的二油�；�磷脂酰乙醇胺（Cy3-DOPE）以相當(dāng)?shù)腄s（中位數(shù)）擴散?=?5.8 和6.2?m2/秒），表明基于肌動蛋白的膜骨架僅將Bdp-Chol的D降低了泡狀PM的約2倍，而將Cy3-DOPE的D降低約20倍。

這些結(jié)果與之前提出的模型一致，在該模型中，PM被基于肌動蛋白的膜骨架柵欄及其相關(guān)的跨膜尖樁蛋白分隔，用于所有膜分子的宏觀擴散，并表明Bdp-Chol一旦進入邊界，通過隔室邊界的概率比Cy3-DOPE大約10倍。由于隔室尺寸大于假定的筏域，我們得出結(jié)論，筏域與膜骨架誘導(dǎo)的隔室共存，并包含在其中。

相關(guān)推薦：

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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