Specific interaction between casein kinase 2 and the nucleolar protein Nopp140

Dongxia Li, U. Thomas Meier, Grazyna Dobrowolska, Edwin G. Krebs

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92 Scopus citations


Casein kinase 2 (CK2) is a multifunctional second messenger-independent protein serine/threonine kinase that phosphorylates many different proteins. To understand the function and regulation of this enzyme, biochemical methods were used to search for CK2-interacting proteins. Using immobilized glutathione S-transferase fusion proteins of CK2, the nucleolar protein Nopp140 was identified as a CK2-associated protein. It was found that Nopp140 binds primarily to the CK2 regulatory subunit, β. The possible in vivo association of Nopp140 with CK2 was also suggested from a coimmunoprecipitation experiment in which Nopp140 was detected in immunoprecipitates of CK2 prepared from cell extracts. Further studies using an overlay technique with radiolabeled CK2 as a probe revealed a direct CK2- Nopp140 interaction. Using deletion mutants of CK2β subunits, the binding region of the CK2β subunit to Nopp140 has been mapped. It was found that the NH2-terminal 20 amino acids of CK2β are involved. Since Nopp140 has been identified as a nuclear localization sequence-binding protein and has been shown to shuttle between the cytoplasm and the nucleus, the finding of a CK2- Nopp140 interaction could shed light on our understanding of the function and regulation of CK2 and Nopp140.

Original languageEnglish (US)
Pages (from-to)3773-3779
Number of pages7
JournalJournal of Biological Chemistry
Issue number6
StatePublished - 1997
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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