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KMID : 0603820060120040419
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Journal of Experimental & Biomedical Science
2006 Volume.12 No. 4 p.419 ~ p.425
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Heat Shock Protein 90{beta} Inhibits Phospholipase C{gamma}-1 Activity in vitro
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Cho Sang-Min
Kim Sung-Kuk
Jang Jong-Soo
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Abstract
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Phospholipase C-{gamma}1;(PLC-{gamma}1) is an important signaling molecule for cell proliferation and differentiation. PLC-{gamma}1 contains two pleckstrin homology (PH) domains, which are responsible for protein-protein interaction and protein-lipid interaction. PLC-{gamma}1 also has two Src homology (SH)2 domains and a SH3 domain, which are responsible for protein- protein interaction. To identity proteins that specifically binds to PH domain of PLC-{gamma}1, we prepared and incubated the glutathione S-transferase(GST)-fused PH domains of PLC-{gamma}1 with COS7 cell lysate. We found that 90 kDa protein specifically binds to PH domain of PLC-{gamma}1. By matrix-assisted laser desorption ionization time of flight-mass spectrometry, the 90 kDa protein revealed to be heat shock protein (Hsp) 90{beta}. Hsp 90{beta} is a molecular chaperone that stabilizes and facilitates the folding of proteins that are involved in cell signaling, including receptors for steroids hormones and a variety of protein kinases. To know whether Hsp 90{beta} affects on PLC-{gamma}1 activity, we performed PIP_2 hydrolyzing activity of PLC-{gamma}1 in the presence of purified Hsp 90{beta} in vitro. Our results show that the Hsp 90{beta} dose-dependently inhibits the enzymatic activity of PLC-{gamma}1 and further suggest that Hsp 90{beta} regulates cell growth and differentiation via regulation of PLC-{gamma}1 activity.
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KEYWORD
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Phospholipase C-{gamma}1, Heat shock protein 90{beta}, GST pull down assay, PIP_2-hydrolysis
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