p300 core domain (a) HAT domain of p300 (green) overlaid with p300 catalytic core (HAT domain in marine, RING domain in gold, PHD domain in cyan, Bromodomain in dark teal, substrate binding loop in red, Lys-CoA in purple) (PDB codes: 3BIY, 4BHW). (b) Zoomed in view of select interactions between RING and HAT domains of p300. (c) Linear representation of select interactions between the p300 RING and HAT domains. Dashed lines represent interactions. Secondary structure naming corresponds to primary texts.