SOS1 as a regulator of phospholipase C-gl

Myung Jong Jkim, Jong Soo Chang, Fuchun Si, Jong-Ik Hwang, Sung H. Ryu, Pann Ghill Suhn

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Abstract

The SH3 domain of PLC-gl has been known to be responsible for the mitogenu effect of PLC-gl and also to be implicated in the control of the lipase activity of the PLC-gl protein. However, little is known about the putative effector pro teins that bind to the PLC-gl SH3 domain. We provide evidence that SOSl, one of the activators of p21 Ras, binds to the SH3 domain of PLC-gl. SOSl co-precipitated with the GST-fused SH3 domain of PLC-gl in vitro. The inter action between SOSl and PLC-gl is mediated by direct physical interaction. Moreover, the C-terminal proline-rich domain of SOSl is involved in the inter action with the PLC-gl SH3 domain. PLC-gl could be co-immunoprecipitated with SOSl antibody. The association between SOSl and SH3 domain of PLC-gl was not influenced by either the activation of the EGF receptor or v-Src-induced transformation in vitro. However, in vivo association between SOSl and PLCgl was slightly potenciated by the activation of EGF-receptor. Furthermore, in transient expression studies with COS-7 cells, we characterized the association between PLC-gl and SOSl in vivo. We could demonstrate that the SH3 domain of PLC-gl is absolutely required for the association with SOSl in vivo. SOSl over-expression in COS-7 cells inhibited EGF-induced Pi-turnover and EGFinduced tyrosyl phosphorylation of PLC-gl. Based on all these observations together, we propose that SOSl may act as a possible regulator in a PLC-gl mediated signaling pathway.

Original languageEnglish
JournalFASEB Journal
Volume12
Issue number8
Publication statusPublished - 1998 Dec 1
Externally publishedYes

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ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology

Cite this

Jkim, M. J., Chang, J. S., Si, F., Hwang, J-I., Ryu, S. H., & Suhn, P. G. (1998). SOS1 as a regulator of phospholipase C-gl. FASEB Journal, 12(8).