Brazill D T, Gundersen R, Gomer R H
Howard Hughes Medical Institute, Department of Biochemistry and Cell Biology, Houston, TX 77251-1892, USA.
FEBS Lett. 1997 Mar 3;404(1):100-4. doi: 10.1016/s0014-5793(97)00104-x.
Starving Dictyostelium discoideum cells monitor the local density of other starving cells by simultaneously secreting and sensing CMF. CMF regulates signal transduction through the chemoattractant cAMP receptor, cAR1. cAR1 activates a heterotrimeric G protein by stimulating G alpha 2 to release GDP and bind GTP. We show here that the rate of cAMP-stimulated GTP hydrolysis in membranes from cells exposed to CMF is roughly 4 times slower than in membranes from untreated cells, even though the rate of GTP binding is the same. This hydrolysis is abolished in cells lacking G alpha 2. Our data thus suggest that CMF regulates cAMP signal transduction in part by prolonging the lifetime of the G alpha 2-GTP complex.
饥饿的盘基网柄菌细胞通过同时分泌和感知CMF来监测其他饥饿细胞的局部密度。CMF通过趋化因子cAMP受体cAR1调节信号转导。cAR1通过刺激Gα2释放GDP并结合GTP来激活异源三聚体G蛋白。我们在此表明，暴露于CMF的细胞的膜中，cAMP刺激的GTP水解速率比未处理细胞的膜中慢约4倍，尽管GTP结合速率相同。在缺乏Gα2的细胞中，这种水解被消除。因此，我们的数据表明，CMF部分通过延长Gα2-GTP复合物的寿命来调节cAMP信号转导。
