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Updated: Aug 9, 2026

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle
Published on: March 5, 2019
A Small Ras-like protein Ray/Rab1c modulates the p53-regulating activity of PRPK
Yasuhito Abe1, Takashi Takeuchi, Yoshinori Imai
1Department of Pathology, Division of Molecular Pathology, National University Corporation, Ehime University School of Medicine, Toh-on, Ehime 791-0295, Japan. yasuhito@m.ehime-u.ac.jp
Abstract:
PRPK phosphorylates serine-15 residue of p53 and enhances transcriptional activity. PRPK possesses a bipartite nuclear localization signal and localizes in nucleus when over-expressed in cells. However, intrinsic PRPK localizes mainly in the cytosol in situ. While studying the mechanisms in the distribution of intrinsic PRPK, we identified a PRPK binding protein, an ubiquitously expressed Small Ras-like GTPase, Rab1c, also named Ray or Rab35. The over-expressed Ray was distributed in the nucleus, cytosol, and cell membrane. Both Ray wild type and GTP-restrictively binding mutant Ray-Q67L, but not guanine nucleotide unstable binding mutant Ray-N120I, partially distributed the over-expressed PRPK to the cytosol and also suppressed the PRPK-induced p53-transcriptional activity profoundly. A Small Ras-like GTPase protein Ray was thus indicated to modulate p53 transcriptional activity of PRPK.
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