In vitro activation of Stat3 by epidermal growth factor receptor kinase.
Proc Natl Acad Sci U S A
; 93(24): 13704-8, 1996 Nov 26.
Article
em En
| MEDLINE
| ID: mdl-8942998
ABSTRACT
Stat proteins are SH2 domain-containing transcription factors that are activated in cells by various cytokines and growth factors. In the case of cytokines whose receptors lack protein kinase activity, phosphorylation-activation is mediated by members of the JAK family of tyrosine protein kinases. In the case of growth factors whose receptors have intrinsic tyrosine protein kinase activity, it is thought that Stat proteins can be activated either directly by the receptor or indirectly through JAK proteins. To test the possibility of direct activation, we have used purified Stat3 alpha, Stat3 beta, and epidermal growth factor receptor kinase produced in recombinant baculovirus-infected Sf9 insect cells. The Stat proteins formed a stable complex with the receptor kinase, and they were phosphorylated on tyrosine by the receptor kinase and activated for binding to DNA, properties shared with Stat proteins purified from Sf9 cells coexpressing JAK1 or JAK2. Both JAK-phosphorylated Stat3 beta and Stat3 beta phosphorylated in vitro by the receptor kinase were 20-50 times more active on a molar basis for DNA binding than phosphorylated Stat3 alpha. We conclude that Stat3 isoforms can be directly phosphorylated and thereby activated in vitro by the epidermal growth factor receptor kinase.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Transativadores
/
Proteínas Proto-Oncogênicas
/
Proteínas de Ligação a DNA
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Receptores ErbB
Limite:
Animals
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
1996
Tipo de documento:
Article