Nanahoshi M, Tsujishita Y, Tokunaga C, Inui S, Sakaguchi N, Hara K, Yonezawa K
Biosignal Research Center, Kobe University, Japan.
FEBS Lett. 1999 Mar 5;446(1):108-12. doi: 10.1016/s0014-5793(99)00189-1.
The catalytic activity of the C subunit of serine/threonine phosphatase 2A is regulated by the association with A (PR65) and B subunits. It has been reported that the alpha4 protein, a yeast homolog of the Tap42 protein, binds the C subunit of serine/threonine phosphatase 2A and protein phosphatase 2A-related protein phosphatases such as protein phosphatase 4 and protein phosphatase 6. In the present study, we showed that alpha4 binds these three phosphatases and the association of alpha4 reduces the activities of these phosphatases in vitro. In contrast, PR65 binds to the C subunit of serine/threonine phosphatase 2A but not to protein phosphatase 4 and protein phosphatase 6. These results suggest that the alpha4 protein is a common regulator of the C subunit of serine/threonine phosphatase 2A and protein phosphatase 2A-related protein phosphatases.
丝氨酸/苏氨酸磷酸酶2A的C亚基的催化活性受与A（PR65）和B亚基结合的调控。据报道，α4蛋白是Tap42蛋白的酵母同源物，可结合丝氨酸/苏氨酸磷酸酶2A的C亚基以及与蛋白磷酸酶2A相关的蛋白磷酸酶，如蛋白磷酸酶4和蛋白磷酸酶6。在本研究中，我们发现α4可结合这三种磷酸酶，且α4的结合在体外会降低这些磷酸酶的活性。相比之下，PR65可结合丝氨酸/苏氨酸磷酸酶2A的C亚基，但不结合蛋白磷酸酶4和蛋白磷酸酶6。这些结果表明，α4蛋白是丝氨酸/苏氨酸磷酸酶2A的C亚基以及与蛋白磷酸酶2A相关的蛋白磷酸酶的共同调节因子。
