Abstract: Receptor recognition factors exist that recognizes the specific cell receptor to which a specific ligand has been bound, and that may thereby signal and/or initiate the binding of the transcription factor to the DNA site. The receptor recognition factor is in one instance, a part of a transcription factor, and also may interact with other transcription factors to cause them to activate and travel to the nucleus for DNA binding. The receptor recognition factor appears to be second-messenger-independent in its activity, as overt perturbations in second messenger concentrations are of no effect. The concept of the invention is illustrated by the results of studies conducted With interferon (IFN)-stimulated gene transcription, and particularly, the activation caused by both IFN&agr; and IFN&ggr;. Specific DNA and amino acid sequences for various human and murine receptor recognition factors are provided, as are polypeptide fragments of two of the ISGF-3 genes, and antibodies have also been prepared and tested.

Abstract: The invention identifies an interface domain for interaction between two or more dimers of Signal Transducer and Activator of Transcription (STAT) proteins formed between amino acid residues Gln8 (Q8), Ile12 (I12), and Leu15 (L15) of &agr; helices 1 and 2, Met28 (M28) and Glu29 (E29) of &agr; helix 3 of a first STAT protein partner of the dimer, and Leu77 (L77) and Leu78 (L78) in &agr; helix 7 of a second STAT protein partner of the dimer. The interface domain is useful for designing and identifying compounds capable of enhancing or inhibiting binding between STAT protein dimers and/or DNA binding sites, and thus useful for identifying compounds able to modulate STAT protein dimer-dimer induction of gene expression.

Abstract: HNF-4 (hepatocyte nuclear factor 4) is a protein enriched in liver extracts that binds to sites required for the transcription of the transthyretin (TTR) and apolipoprotein CIII (apoCIII) genes (Costa et al., 1989; Costa et al., 1990; Leff et al., 1989). We have purified HNF-4 protein (54 kD) and isolated a cDNA clone encoding the protein. HNF-4 is a member of the steroid hormone receptor superfamily with an unusual amino acid in the conserved “knuckle” of the first zinc finger (DGCKG). This and the fact that HNF-4 does not bind significantly to estrogen, thyroid hormone or glucocorticoid response elements indicate that HNF-4 may represent a new subfamily. HNF-4 binds to its recognition site as a dimer and activates transcription in a sequence-specific fashion in nonhepatic (HeLa) cells. HNF-4 mRNA is present in kidney and intestine as well as liver but is absent in other tissues.

Abstract: The present invention describes methods of producing milligram quantities of three forms of purified Stat1 protein from recombinant DNA constructs. In addition, the Stat proteins may be isolated in their phosphorylated or nonphosphorylated forms (Tyr 701). The proteins can be produced in baculovirus infected insect cells, or E. coli. A compact domain in the amino terminus of Stat1&agr; was isolated and found to enhance DNA binding due to its ability to interact with a neighboring Stat protein. A relatively protease-resistant recombinant truncated form of the Stat protein was isolated in 40-50 mg quantities. Purification of the Stat proteins were performed after modifying specific cysteine residues of the Stat proteins to prevent aggregation. Activated EGF-receptor partially purified from membranes by immunoprecipitation was shown to be capable of in vitro catalysis of the phosphorylation of the tyrosine residue of Stat1 known to be phosphorylated in vivo.

Abstract: The present invention provides a crystal containing the N-terminal domain of a STAT protein that is of sufficient quality to perform X-ray crystallographic studies. Methods of preparing the crystals are include in the invention. The present invention further discloses the three-dimensional structure of the crystal. The present invention also provides methods of using the structural information in drug discovery and drug development.

Abstract: The present invention relates to methods for identifying interacting regions of transcription factors, and methods for identifying agents which modulate the interactions, useful for affecting gene regulation, for example, cellular transformation. A site within residues 130-154 and within residues 343-358 in Stat3 were found to interact with the transcription factor c-Jun. On c-Jun, a site within residues 105 and 334, and more particularly, between 105 and 263, interact with Stat3. These sites of interactions permit methods for identifying agents which modulate the interaction between these transcription factors to modulate gene transcription.