TY - JOUR
T1 - Stress-inducible, murine protein mSTI1
T2 - Characterization of binding domains for heat shock proteins and in vitro phosphorylation by different kinases
AU - Lässle, Michael
AU - Blatch, Gregory L.
AU - Kundra, Vikas
AU - Takatori, Toshiro
AU - Zetter, Bruce R.
PY - 1997
Y1 - 1997
N2 - 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 InSTIl 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 InSTI1. pp70(s6k), pp90(rsk), and mitogen-activated protein kinase-activated protein kinase 2 were tested as possible STI1 kinases in vitro using recombinant mSTI1 as a substrate: only pp90(rsk) 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.
AB - 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 InSTIl 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 InSTI1. pp70(s6k), pp90(rsk), and mitogen-activated protein kinase-activated protein kinase 2 were tested as possible STI1 kinases in vitro using recombinant mSTI1 as a substrate: only pp90(rsk) 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.
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U2 - 10.1074/jbc.272.3.1876
DO - 10.1074/jbc.272.3.1876
M3 - Article
C2 - 8999875
AN - SCOPUS:0031036746
SN - 0021-9258
VL - 272
SP - 1876
EP - 1884
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 3
ER -