Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
Cells. 2019 Oct 13;8(10):1246. doi: 10.3390/cells8101246.
Heterotrimeric G-proteins along with G-protein-coupled receptors (GPCRs) regulate many biochemical functions by relaying the information from the plasma membrane to the inside of the cell. The lipid modifications of Gα and Gγ subunits, together with the charged regions on the membrane interaction surface, provide a peculiar pattern for various heterotrimeric complexes. In a previous study, we found that Gαs and Gαi prefer different types of membrane-anchor and subclass-specific lipid domains. In the present report, we examine the role of distinct Gγ subunits in the membrane localization and spatiotemporal dynamics of Gαs and Gαi heterotrimers. We characterized lateral diffusion and G-protein subunit interactions in living cells using fluorescence recovery after photobleaching (FRAP) microscopy and fluorescence resonance energy transfer (FRET) detected by fluorescence lifetime imaging microscopy (FLIM), respectively. The interaction of Gγ subunits with specific lipids was confirmed, and thus the modulation of heterotrimeric G-protein localization. However, the Gα subunit also modulates trimer localization, and so the membrane distribution of heterotrimeric G-proteins is not dependent on Gγ only.
三聚体 G 蛋白与 G 蛋白偶联受体 (GPCR) 通过将信息从质膜传递到细胞内部来调节许多生化功能。Gα 和 Gγ 亚基的脂质修饰，以及膜相互作用表面上的带电区域，为各种三聚体复合物提供了独特的模式。在之前的研究中，我们发现 Gαs 和 Gαi 偏爱不同类型的膜锚定和亚类特异性脂质结构域。在本报告中，我们研究了不同的 Gγ 亚基在 Gαs 和 Gαi 三聚体的膜定位和时空动力学中的作用。我们分别使用荧光恢复后漂白 (FRAP) 显微镜和荧光寿命成像显微镜 (FLIM) 检测的荧光共振能量转移 (FRET) 来表征活细胞中的侧向扩散和 G 蛋白亚基相互作用。证实了 Gγ 亚基与特定脂质的相互作用，从而调节三聚体 G 蛋白的定位。然而，Gα 亚基也调节三聚体的定位，因此三聚体 G 蛋白的膜分布不仅取决于 Gγ。
