CPB/p300 component

The Creb-binding protein (CPB) is not a component of the enhanceosome, but is recruited as a coactivator by the stable structure, and appears to play an important role in the initiation of transcription of the INF- gene. Experiments have clearly demonstrated that recruitment of CPB increases transcription. Current thinking holds that this is due to increased synergetic interactions between the activators forming the enhanceosome and the basal transcription complex (Pol II, SRB's, TFIIF, TFIIH ...). It has been proposed that the CPB/p300 element forms a bridge between the enhanceosome and the RNA Pol II holoenzyme. It is believed that the CPB complex attaches to the newly-formed enhanceosome surface via its amino terminus, while simultaneously interacting with the Pol II holoenzyme via its carboxyl end. This also permits contact between the p65 activation domain of the NF-B element and the transcription factors in the basal complex.

References:

Merika, M. et al., Recruitment of CPB/p300 by the INF Enhanceosome is Required for Synergistic Activation of Transcription, Molecular Cell, 1, pp.277-287 (1998)

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