Characterization of a protein that regulates the DNA-binding activity of NF-AT, the nuclear factor of activated T cells.
NF-AT is a T-cell-restricted activity that regulates interleukin 2 expression by binding to positions -285 to -254 of the interleukin 2 gene. Prior studies have shown that NF-AT is found only in T cells that are appropriately stimulated with "two signals" and is sensitive to the immunosuppressive drugs cyclosporin A and FK506. However, NF-AT has yet to be characterized biochemically. Here we show that the activity of NF-AT in electrophoretic gel mobility-shift assays is greatly enhanced by a distinct protein with an apparent molecular mass of 28 kDa. This modulator has been enriched from the flow-through of NF-AT affinity columns and enhances by severalfold the activity of the factor that elutes from these columns. The modulator has a predominantly nuclear location, but unlike NF-AT, the modulator is found in nuclear extracts of many cell types, even unstimulated T cells and T cells immunosuppressed with cyclosporin A or FK506. This modulator protein may regulate NF-AT binding activity posttranscriptionally, and it should prove useful in the isolation and biochemical characterization of NF-AT.
Granelli-Piperno
A
A
Laboratory of Cellular Physiology and Immunology, Rockefeller University, New York, NY 10021.
McHugh
P
P
D001483:Base Sequence; D002467:Cell Nucleus / Q000502:physiology*; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D016572:Cyclosporine / Q000494:pharmacology; D003600:Cytosol / Q000502:physiology; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics*; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009000:Monocytes / Q000502:physiology*; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D016559:Tacrolimus / Q000494:pharmacology
D015342:DNA Probes; D004268:DNA-Binding Proteins; D007376:Interleukin-2; D009687:Nuclear Proteins; D016572:Cyclosporine; D016559:Tacrolimus