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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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COS Cells / metabolism
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Carcinoma, Hepatocellular / drug therapy
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Carcinoma, Hepatocellular / metabolism
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Cross Reactions
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Cytoplasm / drug effects
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Cytoplasm / metabolism*
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DNA-Binding Proteins / drug effects
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DNA-Binding Proteins / immunology
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DNA-Binding Proteins / metabolism*
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Dimerization
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Humans
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Interleukin-6 / metabolism
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Interleukin-6 / pharmacology
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Liver Neoplasms / drug therapy
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Liver Neoplasms / metabolism
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Melanoma / drug therapy
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Melanoma / metabolism
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Molecular Sequence Data
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Phosphorylation
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Precipitin Tests
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STAT1 Transcription Factor
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STAT3 Transcription Factor
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Trans-Activators / drug effects
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Trans-Activators / immunology
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Trans-Activators / metabolism*
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Transfection
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Tumor Cells, Cultured
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Tyrosine / metabolism
Substances
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DNA-Binding Proteins
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Interleukin-6
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STAT1 Transcription Factor
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STAT1 protein, human
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STAT3 Transcription Factor
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STAT3 protein, human
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Trans-Activators
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Tyrosine