Kim Yun-Kyeong, Jin Youngnam, Vukoti Krishna M, Park Joon Kyu, Kim Eunice E, Lee Kong-Joo, Yu Yeon Gyu
Division of Life Sciences, Korea Institute of Science and Technology, 39-1, Hwawolkok-dong, Songbuk-ku, 136-791 Seoul, South Korea.
Protein Expr Purif. 2003 Oct;31(2):260-4. doi: 10.1016/s1046-5928(03)00194-3.
Human nucleolar phosphoprotein 140, hNopp140, is one of the most highly phosphorylated mammalian proteins, which is involved in the biogenesis of nucleolus. It regulates the transcription of rDNA and has a tendency to bind to doxorubicin, which is widely used as an anti-cancer drug. The biochemical and biophysical property of hNopp140 has not been reported due to the fact that it is rather difficult to obtain protein in large enough quantity. In this paper, we report the cloning and overexpression of the soluble form of hNopp140 in Escherichia coli. The protein was purified to more than 90% homogeneity using hydroxyapatite and ion exchange chromatography. The purified protein can be extensively phosphorylated by casein kinase II and oligomerized into an insoluble aggregate in the presence of magnesium, carbonate, and fluoride ions.
