IDENTIFICATION OF CHANNEL SITES ON G BETA GAMMA SUBUNITS

G蛋白门控内向整流钾离子通道（GIRK）是第一个 这种蛋白质的功能被证明是通过直接相互作用来调节的， 与GTP结合（G）蛋白的β γ亚基（Logothetis等， 1987年）。在FIRCA中，他们提出鉴定G β亚基中的区域， 与GIRK通道相互作用。虽然Gbeta 1-beta4可以激活GIRK 具有类似效率的通道，Gbeta 5未能做到这一点，尽管它显示 完整表达。他们将使用Gbeta 1和Gbeta 5之间的嵌合策略 以确定两种亚型之间负责 它们刺激GIRK活性的能力不同。因为他们已经 将区域缩小到95个氨基酸，他们将进一步缩小这个范围， 区域利用类似的嵌合方法，以便通过定点 突变，他们可以确定负责的特定氨基酸残基 两种β亚基之间的功能差异使用删除 突变的方法，他们将试图确定最小的G β区 能够绑定信道。设计能够影响 通道活性将跟随最小G β区域的鉴定。

The G protein-gated inwardly rectifying K+ (GIRK) channel was the first example of a protein whose function was shown to be regulated by direct interactions with the betagamma subunits of GTP-binding (G) proteins (Logothetis et al., 1987). In this FIRCA they proposed to identify the region(s) in Gbeta subunits that interact(s) with GIRK channels. While Gbeta1-beta4 can activate GIRK channels with similar efficiency, Gbeta5 fails to do so even though it shows intact expression. They will use a chimeric strategy between Gbeta1 and Gbeta5 to identify the region between the two isoforms that is responsible for the difference in their abilities to stimulate GIRK activity. As they have already narrowed the region down to 95 amino acids, they will further narrow down this region utilizing a similar chimeric approach, so that through site-directed mutagenesis they can identify the specific amino acid residues responsible for the functional differences between the two beta subunits. Using a deletion mutagenesis approach they will attempt to identify the minimal Gbeta regions capable of binding the channel. Design of Gbeta peptides capable of affecting channel activity will follow identification of the minimal Gbeta regions.