Ultrafine membrane compartments for molecular diffusion as revealed by single molecule techniques
Ultrafine membrane compartments for molecular diffusion as revealed by single molecule techniques
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DOI：
10.1529/biophysj.103.035717
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发表时间：
2004-06-01
影响因子：
3.4
通讯作者：
Kusumi, A
中科院分区：
文献类型：
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作者：
Murase, K;Fujiwara, T;Kusumi, A
质膜区室由锚定在膜骨架上的跨膜蛋白（锚定蛋白桩模型）界定，将为膜提供基本的镶嵌性，因为它们会影响细胞膜中几乎所有分子的运动。了解细胞膜的这种基本区室结构对于进一步研究各种膜功能至关重要。在这里，使用不饱和磷脂 DOPE 的高时间分辨率单粒子跟踪和单荧光分子视频成像，我们发现质膜区室通常存在于各种细胞类型中，包括 CHO、HEPA-OVA、PtK2、FRSK、HEK293、HeLa、T24 (ECV304) 和 NRK 细胞。隔室尺寸从 30 到 230 nm 不等，而 DOPE 跨越两个相邻隔室之间边界的平均跳跃率范围在 1 到 17 ms 之间。当 DOPE 已经位于边界时，通过隔室屏障的概率也取决于细胞类型，总体变化类似于 7。这些结果强烈表明质膜概念范式转变的必要性：从二维流体连续体模型到区室化膜模型，其中其组成分子在区室中进行跳跃扩散。
Plasma membrane compartments, delimited by transmembrane proteins anchored to the membrane skeleton (anchored-protein picket model), would provide the membrane with fundamental mosaicism because they would affect the movement of practically all molecules incorporated in the cell membrane. Understanding such basic compartmentalized structures of the cell membrane is critical for further studies of a variety of membrane functions. Here, using both high temporal-resolution single particle tracking and single fluorescent molecule video imaging of an unsaturated phospholipid, DOPE, we found that plasma membrane compartments generally exist in various cell types, including CHO, HEPA-OVA, PtK2, FRSK, HEK293, HeLa, T24 (ECV304), and NRK cells. The compartment size varies from 30 to 230 nm, whereas the average hop rate of DOPE crossing the boundaries between two adjacent compartments ranges between 1 and 17 ms. The probability of passing a compartment barrier when DOPE is already at the boundary is also cell-type dependent, with an overall variation by a factor of similar to7. These results strongly indicate the necessity for the paradigm shift of the concept on the plasma membrane: from the two-dimensional fluid continuum model to the compartmentalized membrane model in which its constituent molecules undergo hop diffusion over the compartments.