钾通道GIRK4中G蛋白βγ亚基结合区的研究

Identification of the Gβγ binding regions in G protein-activated inwardly rectifying potassium channel GIRK4

G蛋白激活的内向整流型钾通道 (GIRK)在调节心肌房室细胞和神经元的兴奋性中具有重要作用。为了深入阐明G蛋白βγ亚基激活钾通道的分子机制 ,运用系统缺失突变和重组蛋白体外结合方法 ,研究GIRK4分子中能够与G蛋白βγ亚基结合的区域。结果表明 ,GIRK4N端膜内域中的 4 192区和C端膜内域中的 2 5 334 8区分别是G蛋白βγ亚基的最小结合区域。这一研究为进一步确定Gβγ激活GIRK通道的调节位点 。

G protein activated inwardly rectifying potassium channels (GIRKs), a member of the family of inward rectifying potassium channels, are membrane proteins that conduct K + currents for near the resting membrane potential, and are important in controlling atrial and neuronal cell excitability. To understand the molecular basis for the activation of GIRKs via the βγ subunits of G proteins, the systematic deletion mutagenesis approach and in vitro bind assay for recombinant proteins were used to identify the Gβγ binding regions in GIRK4. The results showed that the minimal Gβγ binding domain in the C and N terminus of GIRK4 is 253~348 fragment and 41~92 fragment respectively. These results provided a strong basis for identifying the specific sites and the key amino acid residues in GIRKs for Gβγ regulation.