The nuclear hormone receptor coactivator SRC-1 is a specific target of p300

p300 and its family member, CREB-binding protein (CBP), function as key transcriptional coactivators by virtue of their interaction with the activated forms of certain transcription factors, In a search for additional cellular targets of p300/CBP, a protein-protein cloning strategy, surprisingly identified SRC-1, a coactivator involved in nuclear hormone receptor transcriptional activity, as a p300/CBP interactive protein, p300 and SRC-1 interact, specifically, in vitro and they also form complexes in vivo, Moreover, we show that SRC-1 encodes a new member of the basic helix-loop-helix-PAS domain family and that it physically interacts with the retinoic acrid receptor in response to hormone binding, Together, these results Implicate p300 as a component of the retinoic acid signaling pathway, operating, In part, through specific interaction with a nuclear hormone receptor coactivator, SRC-1.