Chromatin, TAFs, and a novel multiprotein coactivator are required for synergistic activation by Sp1 and SREBP-1a in vitro

Sp1, a promoter selectivity factor, often works with other enhancer-binding proteins to bring on transcription. Synergy seen in vivo between the sterol-regulated factor SREBP-1a and Sp1 at the low-density lipoprotein receptor (LDLR) promoter has been achieved in vitro. A novel multiprotein coactivator, TBP-associated factors (TAFs), and chromatin are necessary in vitro for synergistic activation by SREBP-1a and Sp1. A human cellular fraction with the coactivator CBP in it is able to support high levels of activation that is chromatin dependent.