Transcriptional coactivator that stimulates transcriptional activity by bridging regulatory proteins and TBP, thereby recruiting TBP to promoters occupied by DNA-binding regulators. Expressed in leaves, roots, stems, petioles and shoots. Higher expression in flowers and siliques. Detected in leaf veins through development. Detected only in seeds of 2-3 days after pollination (dap) siliques. Not induced by heat or cold treatments, H(2)O(2), dehydration, high salt, abscisic acid, 2,4-D, ACC, methyl jasmonate or salicylic acid. Belongs to the MBF1 family.