Rab9 GTPase在促进TIP47的受体招募中的作用
K S Carroll1, J Hanna, I Simon
1Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA.
概括
TIP47与活跃的Rab9 GTPase结合,增强其对曼诺6酸盐受体 (MPR) 的亲和力. 这种相互作用对于有效地将MPRs从内体到Golgi转运至关重要,将货物选择与Rab GTPase活动联系起来.
科学领域:
- 细胞生物学 细胞生物学
- 分子和细胞生物学分子和细胞生物学.
- 生物化学 生物化学
背景情况:
- 曼诺-6酸盐受体 (MPR) 调解了从戈尔吉装置到内分泌体的溶解体酸酶的运输.
- TIP47是一种已知的载荷结合蛋白,对MPR从内分泌体反向运输到Golgi来说至关重要.
- 通过TIP47促进这种传输的精确分子机制仍然不完全理解.
研究的目的:
- 为了研究TIP47和Rab9 GTPase之间的相互作用.
- 确定Rab9在调节TIP47在MPR运输中的作用中的作用.
- 为了阐明细胞质载荷选择机械的招募的分子基础.
主要方法:
- 同免疫沉测试检测蛋白质与蛋白质相互作用.
- 在体外结合测试以量化结合亲缘关系.
- 在培养细胞中进行体内运输测定,以评估功能后果.
- 局部定向的突变发生来破坏特定的结合相互作用.
主要成果:
- TIP47直接与Rab9.9的活性,与GTP结合的形式结合.
- 绑定Rab9显著增加了TIP47对其货物的亲和力,即MPR细胞质域.
- 在TIP47上有一个功能性的Rab9结合部位对于TIP47介导的MPR传输在体内刺激至关重要.
- 这些发现表明,有机体对载荷适配器的选择性招募机制.
结论:
- Rab9 GTPase 在内体到戈尔吉运输通路中起到TIP47功能的关键调节者的作用.
- Rab9和TIP47之间的相互作用将货物选择与Rab GTPases的激活状态相结合.
- 这项研究揭示了通过Rab GTPase依赖的细胞突变因子招募介导的有机体特异性囊泡芽的新机制.
相关概念视频
GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
Coat Assembly and GTPases
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Rab Proteins
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
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...
Rab Cascades
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.
Small GTPases - Ras and Rho
Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
Three regulatory proteins control their activity:


