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. 2000 Feb 1;345(Pt 3):417–421.

Cytoplasmic STAT proteins associate prior to activation.

S Haan 1, M Kortylewski 1, I Behrmann 1, W Müller-Esterl 1, P C Heinrich 1, F Schaper 1
PMCID: PMC1220772  PMID: 10642496

Abstract

The commonly accepted model of STAT factor activation at the cytoplasmic part of the receptor assumes that signal transducers and activators of transcription (STATs) are recruited from a cytoplasmic pool of monomeric STAT proteins. Based on a previous observation that non-phosphorylated STAT3-Src homology 2 domains dimerize in vitro, we investigated whether the observed dimerization is of physiological relevance within the cellular context. We show that STAT1 and STAT3 are pre-associated in non-stimulated cells. Apparently, these complexes are not able to translocate into the nucleus. We provide evidence that the event of STAT activation is more complex than previously assumed.

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Selected References

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