STAP-2 is phosphorylated at tyrosine-250 by Brk and modulates Brk-mediated STAT3 activation

Osamu Ikeda, Yuto Miyasaka, Yuichi Sekine, Akihiro Mizushima, Ryuta Muromoto, Asuka Nanbo, Akihiko Yoshimura, Tadashi Matsuda

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


Signal transducing adaptor protein-2 (STAP-2) is a recently identified adaptor protein that contains Pleckstrin and Src homology 2 (SH2)-like domains as well as a YXXQ motif in its C-terminal region. STAP-2 is also known as breast tumor kinase (Brk) substrate (BKS). Our previous studies revealed that STAP-2 binds to signal transducer and activator of transcription 3 (STAT3) and STAT5, and regulates the signaling pathways downstream of them. In the present study, we identified tyrosine-250 (Tyr250) in STAP-2 as a major site of phosphorylation by Brk, using a series of STAP-2 YF mutants and anti-phospho-STAP-2 Tyr250 antibody. Furthermore, overexpression of the STAP-2 Y250F mutant protein affected Brk-mediated STAT3 activation. Importantly, small-interfering RNA-mediated reduction of endogenous STAP-2 expression decreased Brk-mediated STAT3 activation. Taken together, our findings demonstrate that STAP-2 is phosphorylated at Tyr250 by Brk, and plays an important role in Brk-mediated STAT3 activation.

Original languageEnglish
Pages (from-to)71-75
Number of pages5
JournalBiochemical and Biophysical Research Communications
Issue number1
Publication statusPublished - 2009 Jun 19


  • Brk
  • Phosphorylation
  • STAP-2
  • STAT3
  • Transcription

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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