Characterization of the InsP6-dependent interaction between CK2 and Nopp140.
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.
Lee
Won-Kyu
WK
Division of Life Sciences, Korea Institute of Science and Technology, 39-1, Hawolgok-dong, Songbuk-gu, 136-791, Seoul, Republic of Korea.
Lee
Sang-Yeop
SY
Kim
Woo-Il
WI
Rho
Yoon-Hwa
YH
Bae
Young-Seuk
YS
Lee
Cheolju
C
Kim
Ick Young
IY
Yu
Yeon Gyu
YG
D047390:Casein Kinase II / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010833:Phytic Acid / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
C075564:NOLC1 protein, human; D009687:Nuclear Proteins; D010750:Phosphoproteins; D010833:Phytic Acid; D047390:Casein Kinase II