The KIX domains of both CBP and p300 contribute to c-Myb transactivation function in a dose dependent manner.

<p>(A) Schematic showing approximate locations of CBP and p300 domains [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082684#B91" target="_blank">91</a>]. Nuclear receptor interaction domain (NRID), the CREB-binding domain (KIX), Cys/His-rich region-1 (CH1 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082684#B57" target="_blank">57</a>] or transcriptional-adaptor zinc-finger-1, TAZ1), bromodomain (Br), plant homeodomain (PHD), HAT enzymatic region, zinc-binding domain (ZZ), TAZ2 (aka CH3 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082684#B92" target="_blank">92</a>]), and the nuclear receptor binding domain (NCBD). (B) Alignment of the KIX domains of mouse and human p300 and CBP. Amino acids mutated in the KIX domain mutants are indicated with arrows. (C) Pulldown assay with the c-Myb transactivation domain (aa186-325) fused to GST using extracts from wild type (WT) and <i>CBP</i>^KIX/KIX mouse embryonic fibroblasts. Buffer C is extraction buffer without protein. (D) Transient transfection assay showing Gal-c-Myb 186-325 transactivation function is reduced in mouse embryonic fibroblasts having the indicated number of <i>CBP</i> and p300 mutant KIX alleles (one (<i>p300^+/KIX</i> or <i>CBP^+/KIX</i>), two (<i>CBP^KIX/KIX, p300^KIX/KIX</i> or <i>p300^+/KIX</i>;<i>CBP^+/KIX</i>) or three (<i>p300^+/KIX</i>;<i>CBP^KIX/KIX</i> or <i>p300^KIX/KIX</i>;<i>CBP</i>^+/KIX) KIX); wild type MEFs indicated; one MEF isolate of each genotype except wild type (N=2); (mean ± SEM).