P-Rex1限制了GPCRs的激素诱导内部化,而不依赖于其Rac-GEF活动
Martin J Baker1, Elizabeth Hampson2, Priota Islam2
1Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, UK; Cell Signalling Group, Cancer Research UK Manchester Institute, University of Manchester, Wilmslow Road, Manchester, UK.
Cell reports
|October 16, 2025
概括
关氨酸核酸交换因子P-Rex1调节G蛋白合受体 (GPCR) 信号传递和贩运. 通过与Grk2相互作用,P-Rex1限制了GPCR内部化,在血膜上保持活跃的GPCR.
科学领域:
- 细胞生物学 细胞生物学
- 分子生物学分子生物学
- 生物化学 生物化学
背景情况:
- 像P-Rex1这样的关核酸交换因子 (GEF) 是小GTPase信号传递的关键调节者.
- G蛋白结合受体 (GPCRs) 调解多种细胞反应,它们的贩运受到严格控制.
- P-Rex1在GPCR信号传递中的作用已经确立,但其对GPCR贩运的影响仍然不太清楚.
研究的目的:
- 调查P-Rex1在规范GPCR贩运中的作用.
- 确定P-Rex1的GEF活动是否对其对GPCR贩运的影响是必要的.
- 阐明通过P-Rex1控制GPCR内部化的分子机制.
主要方法:
- 同免疫沉试验用于研究蛋白质与蛋白质相互作用.
- 西方斑点测试用于评估蛋白质含量和酸化.
- 基于细胞的测定用于监测GPCR内部化和贩运.
- 缺乏特定域的P-Rex1突变体的表达.
主要成果:
- P-Rex1 抑制了激素刺激的 GPCRs S1PR1,CXCR4,PAR4 和 GLP1R 的内部化.
- 这种抑制是独立于P-Rex1的Rac-GEF活性,并涉及其PDZ,DEP和伊诺西聚酸4-酸酶域.
- P-Rex1阻断了内部化所需的GPCR酸化,并与G蛋白结合受体激酶2 (Grk2) 相互作用.
结论:
- P-Rex1充当了GPCR贩运的关键调节者,限制了对抗剂诱导的内部化.
- P-Rex1利用一个适配器功能,与Grk2相互作用,以维持GPCRs在血上.
- 在GPCR反应中,P-Rex1具有双重作用:通过Rac-GEF活动调解信号,并通过适应器功能控制贩运.
相关概念视频
GPCR Desensitization
7.9K
G protein-coupled receptor (GPCR) signaling plays a crucial role in cell functioning. GPCR desensitization is an equally essential process. It allows cells to respond to changing environments and regain sensitivity to new stimuli while preventing unnecessary stimulation when no longer needed. Prolonged exposure to stimuli leads to GPCR desensitization. It involves blocking the receptors from binding and activating additional G proteins. This inhibits activation of downstream effectors, thereby...
7.9K
GPCRs Regulate Adenylyl Cylase Activity
7.3K
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of...
7.3K
Small GTPases - Ras and Rho
5.2K
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:
5.2K
G-protein Coupled Receptors
131.5K
G-protein coupled receptors are ligand binding receptors that indirectly affect changes in the cell. The actual receptor is a single polypeptide that transverses the cell membrane seven times creating intracellular and extracellular loops. The extracellular loops create a ligand specific pocket which binds to neurotransmitters or hormones. The intracellular loops holds onto the G-protein.
131.5K
Transducer Mechanism: G Protein–Coupled Receptors
4.0K
G Protein–Coupled Receptors (GPCRs) are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to various stimuli. GPCRs regulate critical physiological pathways and are excellent drug targets for treating diseases such as diabetes, cancer, obesity, depression, or Alzheimer's. Nearly 35% of approved drugs implement their therapeutic effects by selectively interacting with specific GPCRs.
GPCRs are also called heptahelical,...
GPCRs are also called heptahelical,...
4.0K
G Protein-coupled Receptors
16.5K
G Protein-Coupled Receptors or GPCRs are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to sensory stimuli such as light, odors, hormones, cytokines, or neurotransmitters.
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
16.5K


