实时可视化激素催化膜裂变和囊泡释放的实时可视化
Thomas J Pucadyil1, Sandra L Schmid
1Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Cell
|December 17, 2008
概括
激素,一个GTPase,通过在生理GTP条件下形成自我限制的组件来驱动膜裂变. 这些动态的胺结构,而不是全球的形状变化,是囊泡释放的关键.
科学领域:
- 细胞生物学 细胞生物学
- 生物化学 生物化学
- 膜动力学 膜动力学
背景情况:
- 动氨酸是一种GTPase,对于细胞中的膜裂变和囊泡形成至关重要.
- 之前的模型提出了动态介质裂变的全球形状变化.
- 动氨酸介导的膜裂变的精确机制仍然不完全理解.
研究的目的:
- 为了研究胺组合和GTP水解在膜裂变中的作用.
- 在生理条件下阐明动胺催化囊泡释放的机制.
- 挑战膜裂变中的活功能的现有模型.
主要方法:
- 开发用于体外裂变试验的"SUPER"模板 (流体支的双层与多余的膜储库).
- 使用光标记蛋白质观察胺组装和行为.
- 在不同条件下在GTP的存在和缺席下分析动动力学.
主要成果:
- 在没有GTP的情况下,dynamin形成了螺旋组件,形成了膜管道,但没有裂变.
- 仅仅添加GTP就会导致动力素分解,而不是裂变,反驳了全球形状变化模型.
- 在连续的GTP下,dynamin在囊泡部形成自我限制的动态组件,驱动裂变.
- 这些组件在催化膜裂变之前表现出强度波动和可变持久性.
结论:
- 膜裂变是由自我限制的动组件介导的,而不是全球GTP驱动的构造变化.
- 胺在囊泡释放中的功能取决于其形成动态循环结构的能力.
- "SUPER"模板系统为研究膜裂变机制提供了一个新的平台.
相关概念视频
Pinching-off of Coated Vesicles
Vesicle budding is orchestrated by distinct cytosolic proteins such as adaptor proteins, coat proteins, and GTPases. To initiate vesicle budding, membrane-bending proteins containing crescent-shaped BAR domains bind to the lipid heads in the bilayer and distort the membrane to form a protein-coated vesicle bud. Adaptors proteins such as AP2 for clathrin-coated vesicles can nucleate on the deformed membrane. Finally, coat proteins such as clathrin or COPI and COPII assemble into a coat forming...
Protein Dynamics in Living Cells
Different fluorescence-based techniques are used to study the protein dynamics in living cells. These techniques include FRAP, FRET, and PET.
Fluorescent recovery after photobleaching (FRAP) is a fluorescent-protein-based detection technique used to quantify protein movement rates within the cell. This method exposes a small portion of the cell to an intense laser beam. The laser beam causes permanent photobleaching of the fluorophore-tagged proteins in the exposed region. As the bleached...
Fluorescent recovery after photobleaching (FRAP) is a fluorescent-protein-based detection technique used to quantify protein movement rates within the cell. This method exposes a small portion of the cell to an intense laser beam. The laser beam causes permanent photobleaching of the fluorophore-tagged proteins in the exposed region. As the bleached...
SNAREs and Membrane Fusion
Once a transport vesicle has recognized its target organelle, the vesicular membrane needs to fuse with the target membrane to unload the cargo. Transmembrane proteins called SNAREs present on organelle membranes and their vesicles, mediate vesicle fusion.
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
Fusion of Secretory Vesicles with the Plasma Membrane
Proteins and neurotransmitters in secretory vesicles can be released from a cell upon vesicle docking, priming, and fusion with the plasma membrane. Vesicles are docked and primed in preparation for the quick exocytosis of their contents in response to a stimulus. The fusion process is mainly carried out by a SNAP Receptor or SNARE complex, consisting of synaptobrevin, syntaxin-1, and SNAP-25.
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...


