这关键区别在异源G蛋白和单体G蛋白之间是否是杂体G蛋白是由α(α),β(β)和伽马(γ)亚基组成的大膜相关G蛋白,而单体G蛋白是仅由膜相关的G蛋白,仅由一个由A组成的G蛋白仅由A组成α亚基。
G蛋白(鸟嘌呤核苷酸结合蛋白)是一种蛋白质家族,充当细胞内部分子开关。他们参与从细胞外部的各种刺激到内部传输信号。G蛋白可以分为两个不同的蛋白质家族:异源G蛋白和单体G蛋白。杂体G蛋白是一种大蛋白,而单体G蛋白是一种小蛋白。
CONTENTS
1。概述和关键差异
2。什么是异类G蛋白
3。什么是单体G蛋白
4。相似性 - 杂体G蛋白和单体G蛋白
5。杂体G蛋白与单体G蛋白的表格形式
6.Summary – Heteromeric G Protein vs Monomeric G Protein
什么是异类G蛋白?
杂体G蛋白是由α(α),β(β)和γ(γ)亚基组成的大G蛋白。杂体G蛋白形成异三聚体复合物。异三聚体和单体G蛋白之间最大的非结构差异是异三聚体G蛋白与其结合cell surface receptor(G protein-coupled receptors) directly. The alpha subunit of heteromeric G protein is usually attached to either aGTPor GDP that serves as an on or off switch for the activation of G protein.

Figure 01: Heteromeric G Protein
当配体与A结合时GPCR,GPCR获取GEF(鸟嘌呤核苷酸交换因子)能力。这通过将α亚基上的GDP交换为GTP来激活G蛋白。GTP与α亚基的结合导致α亚基与G蛋白的其余部分的结构变化和解离。通常,α亚基结合了下游信号级联的膜结合效应子蛋白。Beta-Gamma综合体也可以执行此功能。此外,杂体G蛋白还参与了CAMP/PKA途径,离子通道,MAPK和PI3K等途径。
什么是单体G蛋白?
Monomeric G protein is a small membrane-associated G protein that is made up of only an alpha subunit. The small monomeric G protein is homologous to the alpha subunit of the large heteromeric G protein. This family of small GTPases includes the RAS superfamily, which is further split into subfamilies based on structural, sequence, and functional similarities. Moreover, each subfamily of small GTPases plays a slightly different role vital in the regulation of intracellular signalling pathways.

图02:单体G蛋白
Like the alpha subunit of large heteromeric G protein, small monomeric G protein alternate between an on state (bound to GTP) and an off state (bound to GDP). Therefore, monomeric G proteins function as binary switches that regulate cytosolic signalling pathways. The above GDP/GTP cycling is controlled by two types of regulatory proteins associated with monomeric G proteins. Guanine exchange factors (GEFs) promote the formation of active or GTP bound form of monomeric G protein (RAS protein), while GTPase activating proteins (空白)加速GTPase活性并促进单体G蛋白(RAS蛋白)的非活性或GDP结合形式
杂体G蛋白和单体G蛋白之间的相似之处是什么?
- 杂体G蛋白和单体G蛋白是G蛋白的两种类型。
- 杂体G蛋白的α亚基与单体G蛋白结构相关。
- 两种蛋白质都与GTP结合并将其水解为GDP,从而充当分子开关。
- 两种蛋白质催化的GTP水解速率可以通过间隙蛋白提高。
- 它们通过翻译后脂质修饰将它们束缚在质膜的内表面。
杂体G蛋白和单体G蛋白有什么区别?
是一个大型membrane-associat Heteromeric G蛋白质ed G protein made up of alpha (α), beta (β), and gamma (γ) subunits, while monomeric G protein is a small membrane-associated G protein made up of only the alpha subunit. Thus, this is the key difference between heteromeric G protein and monomeric G protein. Furthermore, heterotrimeric G protein binds to its cell surface receptor (G protein-coupled receptors) directly. On the other hand, monomeric G protein binds to its cell surface receptor (G protein-coupled receptors) indirectly.
下面的信息图列出了杂体G蛋白与单体G蛋白的差异,以与表格形式进行比较。
Summary – Heteromeric G Protein vs Monomeric G Protein
G蛋白是一个蛋白质家族,充当细胞内部分子开关。杂体G蛋白和单体G蛋白是G蛋白的两种类型。杂体G蛋白是一种大型膜相关的G蛋白,由α(α),β(β)和γ(γ)亚基组成。单体G蛋白是仅由α亚基组成的小膜相关G蛋白。因此,这总结了异源G蛋白和单体G蛋白之间的差异。
参考:
1。“异三聚体G蛋白。”概述|ScienceDirect主题。
2.“”Monomeric Guanine Nucleotide Binding Protein。”概述|ScienceDirect主题。
图片提供:
1。“GPCR周期” By Repapetilto – Own work(CC BY-SA 3.0)通过Commons Wikimedia
2.“”类似Ras的G蛋白” A08821156 - 自己的工作(CC BY-SA 3.0)通过Commons Wikimedia
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