Kwok R P, Lundblad J R, Chrivia J C, Richards J P, Bächinger H P, Brennan R G, Roberts S G, Green M R, Goodman R H
Vollum Institute, Oregon Health Sciences University, Portland 97201.
Nature. 1994 Jul 21;370(6486):223-6. doi: 10.1038/370223a0.
The transcription factor CREB binds to a DNA element known as the cAMP-regulated enhancer (CRE). CREB is activated through phosphorylation by protein kinase A (PKA), but precisely how phosphorylation stimulates CREB function is unknown. One model is that phosphorylation may allow the recruitment of coactivators which then interact with basal transcription factors. We have previously identified a nuclear protein of M(r)265K, CBP, that binds specifically to the PKA-phosphorylated form of CREB. We have used fluorescence anisotropy measurements to define the equilibrium binding parameters of the phosphoCREB:CBP interaction and report here that CBP can activate transcription through a region in its carboxy terminus. The activation domain of CBP interacts with the basal transcription factor TFIIB through a domain that is conserved in the yeast coactivator ADA-1 (ref. 8). Consistent with its role as a coactivator, CBP augments the activity of phosphorylated CREB to activate transcription of cAMP-responsive genes.
转录因子CREB可与一种名为cAMP调节增强子（CRE）的DNA元件结合。CREB通过蛋白激酶A（PKA）磷酸化而被激活，但磷酸化具体如何刺激CREB发挥功能尚不清楚。一种模型认为，磷酸化可能会促使共激活因子的募集，然后这些共激活因子与基础转录因子相互作用。我们之前鉴定出一种分子量为265K的核蛋白CBP，它能特异性结合PKA磷酸化形式的CREB。我们利用荧光各向异性测量来确定磷酸化CREB与CBP相互作用的平衡结合参数，并在此报告CBP可通过其羧基末端的一个区域激活转录。CBP的激活结构域通过酵母共激活因子ADA-1中保守的一个结构域与基础转录因子TFIIB相互作用。与其作为共激活因子的作用一致，CBP增强磷酸化CREB激活cAMP反应性基因转录的活性。
