| Autor: |
Lässle, Michael, Blatch, Gregory L., Kundra, Vikas, Takatori, Toshiro, Zetter, Bruce R. |
| Zdroj: |
Journal of Biological Chemistry; January 1997, Vol. 272 Issue: 3 p1876-1884, 9p |
| Abstrakt: |
We have recently isolated the cDNA for the murine homologue of the stress-inducible phosphoprotein STI1 (also known as IEF SSP 3521 or p60). STI1 was previously shown to be 2-fold up-regulated in MRC-5 fibroblasts upon viral transformation and to exist in a macromolecular complex with heat shock proteins of the HSP 70 and 90 families. By peptide-sequencing we have identified the two heat shock proteins that bind to murine STI1 (mSTI1) as HSC 70 and HSP 84/86. We describe two separate binding regions within mSTI1 for the two heat shock proteins. In the presence of cell extracts, the N-terminal region of mSTI1 binds preferentially to HSC 70, whereas the C-terminal portion of the molecule promotes the binding of HSP 84/86. Heat treatment caused a strong induction of mSTI1 message without affecting the steady-state level of the protein significantly. In addition, heat treatment led to changes in the isoform-composition of mSTI1. pp70s6k, pp90rsk, and mitogen-activated protein kinase-activated protein kinase 2 were tested as possible STI1 kinases in vitrousing recombinant mSTI1 as a substrate: only pp90rskwas able to phosphorylate recombinant mSTI1. In vitrokinase assays using casein kinase II suggest serine 189 to be a likely phosphorylation site in mSTI1. |
| Databáze: |
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