“G-蛋白耦合受体”(GPCRs)的激发导致G-蛋白亚单元GG 和 G 从GPCR的细胞内表面上释放。GGG然后可以结合到“由GGG蛋白门控的内向整理器K+”(GIRK) 通道上，并激发后者，使该通道的孔打开。GIRK通道的打开驱动膜电压朝向“静息电位”（“能斯特电位”）变化，这将使膜去极化的速度降低。
在这篇文章中，Matthew Whorton 和 Roderick MacKinnon解决了一个哺乳动物GIRK2通道在通过 G-蛋白亚单元存在时的X-射线晶体结构。虽然射射 G-蛋白亚单元的总体结构实质上与在GG 或 GIRK存在时是一样的，但GIRK 和 GIRK–G 的结构却很不相同。
该结构还显示了起信号作用的脂质PIP2和细胞内Na+离子是怎样帮助调控GIRKs的活性的。(生物谷Bioon.com)
生物谷推荐英文摘要：
Nature doi:10.1038/nature12241
X-ray structure of the mammalian GIRK2–βγ G-protein complex
Matthew R. Whorton & Roderick MacKinnon
G-protein-gated inward rectifier K+ (GIRK) channels allow neurotransmitters, through G-protein-coupled receptor stimulation, to control cellular electrical excitability. In cardiac and neuronal cells this control regulates heart rate and neural circuit activity, respectively. Here we present the 3.5?? resolution crystal structure of the mammalian GIRK2 channel in complex with βγ G-protein subunits, the central signalling complex that links G-protein-coupled receptor stimulation to K+ channel activity. Short-range atomic and long-range electrostatic interactions stabilize four βγ G-protein subunits at the interfaces between four K+ channel subunits, inducing a pre-open state of the channel. The pre-open state exhibits a conformation that is intermediate between the closed conformation and the open conformation of the constitutively active mutant. The resultant structural picture is compatible with ‘membrane delimited’ activation of GIRK channels by G proteins and the characteristic burst kinetics of channel gating. The structures also permit a conceptual understanding of how the signalling lipid phosphatidylinositol-4,5-bisphosphate (PIP2) and intracellular Na+ ions participate in multi-ligand regulation of GIRK channels.
