Lee Won-Kyu, Lee Sang-Yeop, Kim Woo-Il, Rho Yoon-Hwa, Bae Young-Seuk, Lee Cheolju, Kim Ick Young, Yu Yeon Gyu
Division of Life Sciences, Korea Institute of Science and Technology, 39-1, Hawolgok-dong, Songbuk-gu, 136-791, Seoul, Republic of Korea.
Biochem Biophys Res Commun. 2008 Nov 14;376(2):439-44. doi: 10.1016/j.bbrc.2008.09.008. Epub 2008 Sep 13.
Nopp140, a highly phosphorylated nucleolar protein, negatively regulates CK2, a kinase essential for cell proliferation. We quantitatively analyzed the interaction between two subunits of CK2 and Nopp140 and characterized the mechanism by which InsP(6) inhibits the interaction. Nopp140 specifically binds to the catalytic subunit of CK2 (CK2alpha) with a dissociation constant of (K(d)) of 4nM, which interferes with the catalytic activity of CK2. The C-terminal region of Nopp140 is determined as CK2alpha-binding region by a yeast two-hybrid method as well as a direct measurement of the interaction between CK2alpha and deletion mutants of Nopp140. InsP(6) specifically binds to CK2alpha and disrupts the interaction between CK2alpha and Nopp140 with an IC(50) value of 25 microM, thereby attenuating the Nopp140-mediated repression of CK2 activity.
Nopp140是一种高度磷酸化的核仁蛋白，它对CK2具有负调控作用，CK2是细胞增殖所必需的一种激酶。我们定量分析了CK2的两个亚基与Nopp140之间的相互作用，并阐明了肌醇六磷酸（InsP(6)）抑制这种相互作用的机制。Nopp140以4nM的解离常数（K(d)）特异性结合CK2的催化亚基（CK2α），这会干扰CK2的催化活性。通过酵母双杂交方法以及直接测量CK2α与Nopp140缺失突变体之间的相互作用，确定了Nopp140的C末端区域为CK2α结合区域。InsP(6)特异性结合CK2α，并以25μM的半数抑制浓度（IC(50)）破坏CK2α与Nopp140之间的相互作用，从而减弱Nopp140介导的对CK2活性的抑制作用。
