PAP-1, a novel target protein of phosphorylation by Pim-1 kinase

Hiroshi Maita, Yosuke Harada, Daisuke Nagakubo, Hirotake Kitaura, Masako Ikeda, Katsuyuki Tamai, Kazuhiko Takahashi, Hiroyoshi Ariga, Sanae M.M. Iguchi-Ariga

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55 Citations (Scopus)


Protooncogene, pim-1, has been reported to be a predisposition for lymphomagenesis along with myc, and its protein product, Pim-1, has been shown to be a serine/threonine protein kinase, whose activity is involved in proliferation and differentiation of blood cells. The signal transduction pathways neither to nor from Pim-1, however, have been clarified. We have cloned a cDNA encoding a novel Pim-1 binding protein, PAP-1, comprising 213 amino acids with a basic amino-acid cluster near the C-terminus. PAP-1 was colocalized with Pim-1 in human HeLa cell nuclei. The in vitro binding assays using GST fusion proteins of the wild-type and various deletion mutants revealed that the whole molecule of Pim-1 is required for the binding activity to PAP-1 and that Pim-1 binds to the region from amino-acid numbers 1-147 of PAP-1, or to two segments in the region. The association of PAP-1 with Pim-1 was also shown in vivo in transfected cells. Furthermore, PAP-1 was phosphorylated in vitro by Pim-1, but not a kinase-negative Pim-1 mutant. The two serine residues of PAP-1 at amino acids 204 and 206 near the C-terminus were phosphorylated by Pim-1. PAP-1 is thus thought to be a target protein for Pim-1 kinase.

Original languageEnglish
Pages (from-to)5168-5178
Number of pages11
JournalEuropean Journal of Biochemistry
Issue number16
Publication statusPublished - 2000


  • PAP-1
  • Phosphorylation
  • Pim-1


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