Synergistic action of MLL, a TRX protein with template activating factor-I, a histone chaperone

MLL is involved in the process of gene activity maintenance. It is shown that the amino-terminal region of MLL (MLLN) interacts with TAF-Iβ/SET. In this study, using yeast two-hybrid assays, we have found that the acidic region of TAF-Iβ is essential for its binding to MLLN. Pull-down assays using GST-MLLN demonstrated that TAF-Iβ and histones interact with GST-MLLN. MLLN and TAF-Iβ synergistically upregulated the transcription level of Hoxa9 and co-immunoprecipitated in chromatin containing the Hoxa9 promoter region. These results suggest that TAF-Iβ plays an important role in MLL-mediated transcription and possibly chromatin maintenance.