Identification of novel cellular partners involved in controlling reversible dissociation of V-ATPases in vivo

真核细胞已经进化出一个依赖atp的质子泵家族，称为液泡H+- atp酶（v - atp酶）。v -ATP酶存在于各种细胞内的区室中，它们通过以牺牲ATP为代价将质子泵过膜来维持pH稳态。细胞器的酸化在膜运输、蛋白质降解、小分子的耦合运输和各种病原体的进入中是必不可少的。此外，v - atp酶在正常生理过程和许多人类疾病中起着至关重要的作用。调控V-ATPases活性的快速有效机制涉及V1和VO两个功能域的解离和结合。迄今为止，这一过程在酵母中得到了最好的表征，其中v - atp酶在葡萄糖消耗的反应中被可逆地分解。尽管Ras/cAMP/PKA（蛋白激酶A）通路最近被证明在酵母中调节v - atp酶的可逆解离中起作用，但关于PKA与这一过程相关的蛋白质尚不清楚。目前还不清楚v - atp酶的亚基或相关蛋白是否为PKA的底物。本提案将使用一种新的基因筛选方法来寻找参与可逆解离的PKA下游的新蛋白，以识别在这一过程中有缺陷的突变体。实验还将进行测试是否v - atp酶亚基或与复合体相关的蛋白质在可逆解离过程中被磷酸化或去磷酸化。

Eukaryotic cells have evolved a family of ATP-dependent proton pumps known as the vacuolar H+-ATPases (V-ATPases). V-ATPases are present in a variety of intracellular compartments where they are responsible for pH homeostasis by pumping protons across the membrane at the expense of ATP. Acidification of organelles is essential in membrane trafficking, protein degradation, coupled transport of small molecules, and the entry of various pathogens. Furthermore, V-ATPases play a crucial role for normal physiological processes as well as in a number of human diseases. A rapid and effective mechanism for regulating the activity of V-ATPases involves dissociation and association of the two functional domains, V1 and VO. To date, this process is best characterized in yeast, where V-ATPases are reversibly disassembled in response to glucose depletion. Although the Ras/cAMP/PKA (protein kinase A) pathway has recently been shown to function in regulation of reversible dissociation of the V-ATPase in yeast, nothing is known about the proteins that connect PKA to this process. It is also not known whether subunits of the V-ATPase or associated proteins are substrates of PKA. This proposal will search for novel proteins downstream of PKA that are involved in reversible dissociation using a novel genetic screen that identifies mutants defective in this process. Experiments will also be performed to test whether V-ATPase subunits or proteins associated with the complex become phosphorylated or dephosphorylated during reversible dissociation.