Division of Pediatric Endocrinology, Children's Hospital of Pittsburgh, PA, USA.
Cell Signal. 2010 Jul;22(7):1013-21. doi: 10.1016/j.cellsig.2010.02.003. Epub 2010 Feb 17.
In Saccharomyces cerevisiae, Snf1 kinase, the ortholog of the mammalian AMP-activated protein kinase, is activated by an increase in the phosphorylation of the conserved threonine residue in its activation loop. The phosphorylation status of this key site is determined by changes in the rate of dephosphorylation catalyzed by the yeast PP1 phosphatase Glc7 in a complex with the Reg1 protein. Reg1 and many PP1 phosphatase regulatory subunits utilize some variation of the conserved RVxF motif for interaction with PP1. In the Snf1 pathway, the exact role of the Reg1 protein is uncertain since it binds to both the Glc7 phosphatase and to Snf1, the Glc7 substrate. In this study we sought to clarify the role of Reg1 by separating the Snf1- and Glc7-binding functions. We generated a series of Reg1 proteins, some with deletions of conserved domains and one with two amino acid changes in the RVxF motif. The ability of Reg1 to bind Snf1 and Glc7 required the same domains of Reg1. Further, the RVxF motif that is essential for Reg1 binding to Glc7 is also required for binding to Snf1. Our data suggest that the regulation of Snf1 dephosphorylation is imparted through a dynamic competition between the Glc7 phosphatase and the Snf1 kinase for binding to the PP1 regulatory subunit Reg1.
在酿酒酵母中，Snf1 激酶是哺乳动物 AMP 激活蛋白激酶的同源物，其激活是通过其激活环中保守苏氨酸残基的磷酸化增加来实现的。该关键位点的磷酸化状态取决于酵母 PP1 磷酸酶 Glc7 与 Reg1 蛋白复合物催化的去磷酸化速率的变化。Reg1 和许多 PP1 磷酸酶调节亚基利用保守的 RVxF 基序的一些变体与 PP1 相互作用。在 Snf1 途径中，Reg1 蛋白的确切作用尚不确定，因为它既与 Glc7 磷酸酶结合，也与 Glc7 底物 Snf1 结合。在这项研究中，我们试图通过分离 Snf1 和 Glc7 结合功能来阐明 Reg1 的作用。我们生成了一系列 Reg1 蛋白，其中一些缺失了保守结构域，还有一个在 RVxF 基序中有两个氨基酸变化。Reg1 结合 Snf1 和 Glc7 需要 Reg1 的相同结构域。此外，对于 Reg1 与 Glc7 的结合至关重要的 RVxF 基序也需要与 Snf1 结合。我们的数据表明，Snf1 去磷酸化的调节是通过 Glc7 磷酸酶和 Snf1 激酶与 PP1 调节亚基 Reg1 的结合之间的动态竞争来实现的。
