通过固态NMR对磁放松放松增强在脂质双层中不对称插入膜蛋白:一个细胞透的例子
Yongchao Su1, Rajeswari Mani, Mei Hong
1Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Journal of the American Chemical Society
|July 4, 2008
概括
一种新的固态NMR方法揭示了膜蛋白如何插入脂质双层. 这种技术挑战了吸收的电穿孔模型,提出了诸如酸复合的替代机制.
科学领域:
- 生物物理学的生物物理.
- 膜蛋白质结构结构 膜蛋白质结构
- 核磁共振 (NMR) 光谱学 核磁共振 (NMR) 光谱学
背景情况:
- 了解膜蛋白插入对于细胞生物学至关重要.
- 现有的模型,如电穿孔,可能无法完全解释脂质双层之间的转位.
- 精确确定膜内蛋白质残留的侧向性是一项挑战.
研究的目的:
- 介绍一种新的固态NMR技术,以确定膜蛋白的不对称插入深度.
- 研究细胞透的插入机制,特别是透.
- 挑战和完善现有的脂相互作用和膜转移模型.
主要方法:
- 使用了具有 (Mn2+) 离子选择性结合到二层脂质的单片剂的偏磁放松增强剂 (PRE).
- 采用固态NMR检测Mn2+结合时脂质头组信号 (31) P和 (13) C) 的变化.
- 应用了该技术来研究透在不同度的脂质双层中的分布.
主要成果:
- 证明双层的一侧的Mn2+离子可以选择性地抑制脂质头组信号,从而能够确定侧面性.
- 发现透素在低度下分布在两个脂质叶片之间,这与电穿孔模型对外部叶片结合的预测相反.
- 在单侧Mn2+结合的无蛋白膜中观察到显著的残留脂质信号,但在双侧结合中抑制.
结论:
- 新的固态NMR PRE技术有效地识别了膜蛋白的不对称插入深度.
- 这项研究证实了电穿孔模型对于低度透的吸收无效.
- 提出了一种涉及瓜尼迪尼-酸盐复合的替代机制,用于透的细胞内进口.
相关概念视频
Insertion of Single-pass Transmembrane Proteins in the RER
Integral membrane proteins are proteins adhered to the lipid bilayer of a cell organelle or membrane. They can be of two types: transmembrane integral proteins that span the lipid bilayer and monotopic proteins that are attached to either side of the membrane but do not pass through it.
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Insertion of Multi-pass Transmembrane Proteins in the RER
The rough ER membrane synthesizes, assembles, and embeds transmembrane proteins in diverse topologies. These proteins function as transporters or channels and can remain in the ER membrane or are sent to the Golgi complex, lysosome, and cell membrane.
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Protein Diffusion in the Membrane
Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion experiment where mouse and human cells were fused, resulting in hybrid cells. When the human and mouse cells fused, the specific membrane proteins on human and mouse cells were marked with the red and green-fluorescent markers, respectively. Initially, the red and green fluorescence was located on the respective hemisphere of the cell. As time...
Tail-anchoring of Proteins in the ER Membrane
Tail-anchored, or TA, proteins are estimated to make up to 3-5% of membrane proteins found in the eukaryotic cell. Such proteins have a single transmembrane domain located approximately 30 amino acid residues upstream from the C-terminal end. As a result, the signal recognition particle (SRP) cannot guide a TA protein to the ER membrane for cotranslational insertion. Hence, they are integrated into the ER membrane post-translationally using their C-terminal end as the anchor. TA proteins...
Mechanisms of Membrane-bending
The living membranes are flexible due to their fluid mosaic nature; however, their bending into different shapes is an active process regulated by specific lipids and proteins. The membrane bending can be transient as seen in vesicles or stable for a long time as in microvilli. Cells regulate the size, location, and duration of the membrane curvature.
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...

