ik3-1/cables is a substrate for cyclin-dependent kinase 3 (cdk 3)

Tadanori Yamochi, Kentaro Semba, Keitaro Tsuji, Kiyohisa Mizumoto, Hiroko Sato, Yoshiharu Matsuura, Ikuo Nishimoto, Masaaki Matsuoka

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11 Citations (Scopus)


p70ik3-1 (a 70-kDa protein) contains a cyclin box, and binds to p35cdk3 in vivo and in vitro [Matsuoka, M., Matsuura, Y., Semba, K. & Nishimoto, I. (2000) Biochem. Biophys. Res. Commun. 273, 442-447]. In spite of its structural similarity to cyclins, p70ik3-1 does not activate cyclin-dependent kinase 3 (cdk3)-mediated phosphorylation of pRb, histone H1, or the C-terminal domain of RNA polymerase II. Here, we report that Ser274 of p70ik3-1 is phosphorylated by cdk2 or cdk3 bound to cyclin A and to cyclin E in vitro. We also found that in COS7 cells in which cyclin E and cdk3 were ectopically overexpressed, the phosphorylation level of Ser274 in coexpressed p70ik3-1 is upregulated. We therefore conclude that p70ik3-1 is a substrate for cdk3-mediated phosphorylation.

Original languageEnglish
Pages (from-to)6076-6082
Number of pages7
JournalEuropean Journal of Biochemistry
Issue number23
Publication statusPublished - 2001 Dec 27



  • Phosphorylation
  • cdk3
  • ik3-1

ASJC Scopus subject areas

  • Biochemistry

Cite this

Yamochi, T., Semba, K., Tsuji, K., Mizumoto, K., Sato, H., Matsuura, Y., Nishimoto, I., & Matsuoka, M. (2001). ik3-1/cables is a substrate for cyclin-dependent kinase 3 (cdk 3). European Journal of Biochemistry, 268(23), 6076-6082. https://doi.org/10.1046/j.0014-2956.2001.02555.x