Identification and Characterization of the Interaction between Heat-Shock Protein 90 and Phospholipase C-γ1

  • Kim, Su-Jeong (Department of Life Science, and School of Environmental Engineering, Pohang University of Science and Technology) ;
  • Kim, Myung-Jong (Department of Life Science, and School of Environmental Engineering, Pohang University of Science and Technology) ;
  • Kim, Yong (Department of Life Science, and School of Environmental Engineering, Pohang University of Science and Technology) ;
  • Si, Fu Chun (Department of Life Science, and School of Environmental Engineering, Pohang University of Science and Technology) ;
  • Ryu, Sung-Ho (Department of Life Science, and School of Environmental Engineering, Pohang University of Science and Technology) ;
  • Suh, Pann-Chill (Department of Life Science, and School of Environmental Engineering, Pohang University of Science and Technology)
  • Published : 2000.03.31

Abstract

Phosphoinositide-specific phospholipase C-${\gamma}1$ (PLC-${\gamma}1$) is a pivotal mediator in the signal transduction cascades induced by many growth factors. Using a yeast two-hybrid system, heat-shock protein 90 (Hsp90) was identified as a PLC-${\gamma}1$-binding protein. A co-immunoprecipitation experiment, using anti-PLC-${\gamma}1$ antibody, demonstrated an in vivo interaction between Hsp90 and PLC-${\gamma}1$ in the NIH-3T3 cells. The interaction in NIH-3T3 was unaffected by the PDGF treatment, inducing phosphorylation and activation of PLC-${\gamma}1$. Direct interaction between Hsp90 and PLC-${\gamma}1$ was confirmed by in vitro binding experiments using purified Hsp90 and PLC-${\gamma}1$. Furthermore, Hsp90 increased the $PIP_2$-hydrolyzing activity of PLC-${\gamma}1$ up to 2-fold at $0.1{\mu}M$ in vitro. Taken together, we show for the first time, the interaction of PLC-${\gamma}1$ with Hsp90, both in vivo and in vitro. We suggest that Hsp90 may play a role in PLC-${\gamma}1$-mediated signal transduction.

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