Department of Chemistry, University of California Berkeley, Berkeley, California.
NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland.
Biophys J. 2018 Jan 9;114(1):137-145. doi: 10.1016/j.bpj.2017.10.042.
Ras is a membrane-anchored signaling protein that serves as a hub for many signaling pathways and also plays a prominent role in cancer. The intrinsic behavior of Ras on the membrane has captivated the biophysics community in recent years, especially the possibility that it may form dimers. In this article, we describe results from a comprehensive series of experiments using fluorescence correlation spectroscopy and single-molecule tracking to probe the possible dimerization of natively expressed and fully processed K-Ras4B in supported lipid bilayer membranes. Key to these studies is the fact that K-Ras4B has its native membrane anchor, including both the farnesylation and methylation of the terminal cysteine, enabling detailed exploration of possible effects of cholesterol and lipid composition on K-Ras4B membrane organization. The results from all conditions studied indicate that full-length K-Ras4B lacks intrinsic dimerization capability. This suggests that any lateral organization of Ras in living cell membranes likely stems from interactions with other factors.
Ras 是一种膜锚定信号蛋白，作为许多信号通路的枢纽，在癌症中也起着重要作用。近年来，Ras 在膜上的固有行为引起了生物物理界的关注，特别是它可能形成二聚体的可能性。在本文中，我们描述了使用荧光相关光谱和单分子跟踪技术来探测天然表达和完全加工的 K-Ras4B 在支撑脂质双层膜中可能二聚化的一系列综合实验的结果。这些研究的关键是 K-Ras4B 具有其天然的膜锚定，包括末端半胱氨酸的法呢基化和甲基化，这使得可以详细研究胆固醇和脂质组成对 K-Ras4B 膜组织的可能影响。所有研究条件的结果都表明，全长 K-Ras4B 缺乏内在的二聚化能力。这表明，活细胞膜中 Ras 的任何横向组织都可能源于与其他因素的相互作用。
