Lässle, M, Blatch, Gregory ORCID: 0000-0003-0778-8577, Kundra, V, Takatori, T and Zetter, B (1997) Stress-inducible, murine protein mSTI1: Characterization of binding domains for heat shock proteins and in vitro phosphorylation by different kinases. Tthe Journal of Biological Chemistry, 272 (3). pp. 1876-1884. ISSN 0021-9258

Abstract

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 isoformcomposition of mSTI1. pp70s6k, pp90rsk, and mitogenactivated protein kinase-activated protein kinase 2 were tested as possible STI1 kinases in vitro using recombinant mSTI1 as a substrate: only pp90rsk was able to phosphorylate recombinant mSTI1. In vitro kinase assays using casein kinase II suggest serine 189 to be a likely phosphorylation site in mSTI1.

Search Google Scholar

Repository staff login