CLONING OF A CDNA-ENCODING A DNA-BINDING PROTEIN TAXREB302 THAT IS SPECIFIC FOR THE TAX-RESPONSIVE ENHANCER OF HTLV-I

The transcriptional activator, Tax, of human T-cell leukemia virus (HT LV-I) has been considered to interact with cellular proteins to act on target enhancer motifs. Using oligodeoxyribonucleotides containing th e tax-responsive element (TAXRE) of the HTLV-I enhancer, we have clone d multiple cDNAs coding for TAXRE-binding proteins (TAXREB), and deter mined the cDNA and the deduced 200-amino-acid sequences for TAXREB302. The recombinant protein binds to the enhancer DNA by specific interac tion to the CRE-like sequence. A single 1.8-kb species of mRNA was det ected in cultured cells, as well as in normal human tissues, especiall y brain and skeletal muscle. The 22-kDa native protein was detected in the cultured-cell lysate by immunoblotting analysis. TAXREB302 does n ot have structural features common to the CRE-binding protein or activ ating transcription factor (CREB/ATF) family, but has homology to chic ken erythroid transcription factor (Eryf1 or GATA-1), suggesting a pos sible protein-protein interaction.