Interferon activation of the transcription factor Stat91 involves dimerization through SH2-phosphotyrosyl peptide interactions

Ke Shuai, Curt M. Horvath, Linda H.Tsai Huang, Sajjad A. Qureshi, David Cowburn, James E. Darnell

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632 Scopus citations


Stat91 (a 91 kd protein that acts as a signal transducer and activator of transcription) is inactive in the cytoplasm of untreated cells but is activated by phosphorylation on tyrosine in response to a number of polypeptide ligands, including interferon α (IFN-α) and IFN-γ. We report here that the inactive Stat91 in the cytoplasm of untreated cells is a monomer and that upon IFN-γ-induced phosphorylation it forms a stable homodimer. Only the dimer is capable of binding to a specific DNA sequence directing transcription. Through dissociation and reassociation assays, we show that dimerization of Stat91 is mediated through SH2-phosphotyrosyl peptide interactions. Dimerization involving SH2 recognition of specific phosphotyrosyl peptides may well provide a prototype for interactions among family members of STAT proteins to form different transcription complexes.

Original languageEnglish (US)
Pages (from-to)821-828
Number of pages8
Issue number5
Publication statusPublished - Mar 11 1994


ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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