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 acid 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. IMAGES:

p300及其家族成员CREB结合蛋白（CREB-binding protein, CBP）可通过与特定转录因子的活化形式发生相互作用，作为关键的转录辅激活因子行使功能。在搜寻p300/CBP的其他细胞靶标时，研究人员借助蛋白质-蛋白质克隆策略，意外发现参与核激素受体转录活性调控的辅激活因子SRC-1为p300/CBP的互作蛋白。p300与SRC-1可在体外特异性结合，二者在体内亦可形成复合物。此外，本研究证实SRC-1属于碱性螺旋-环-螺旋-PAS结构域（basic helix-loop-helix-PAS domain）家族的新成员，且其能够响应激素结合，与视黄酸受体发生物理性相互作用。综上，上述结果表明p300是视黄酸信号通路的组成组分，其部分功能通过与核激素受体辅激活因子SRC-1的特异性相互作用得以实现。图片：