ISOLATION OF THE CYCLOSPORINE-SENSITIVE T-CELL TRANSCRIPTION FACTOR NFATP

Nuclear factor of activated T cells (NFAT) is a transcription factor t hat regulates expression of the cytokine interleukin-2 (IL-2) in activ ated T cells. The DNA-binding specificity of NFAT is conferred by NFAT p, a phosphoprotein that is a target for the immunosuppressive compoun ds cyclosporin A and FK506. Here, the purification of NFATp from murin e T cells and the isolation of a complementary DNA clone encoding NFAT p are reported. A truncated form of NFATp, expressed as a recombinant protein in bacteria, binds specifically to the NFAT site of the murine IL-2 promoter and forms a transcriptionally active complex with recom binant c-Fos and c-Jun. Antisera to tryptic peptides of the purified p rotein or to the recombinant protein fragment react with T cell NFATp. The molecular cloning of NFATp should allow detailed analysis of a T cell transcription factor that is central to initiation of the immune response.