Ubiquitination of Notch1 is regulated by MAML1-mediated p300 acetylation of Notch1

► p300 acetylates conserved lysines within Notch1 C-terminal nuclear localization signal. ► MAML1 and CSL, components of Notch transcription complex, increase Notch acetylation. ► MAML1-dependent acetylation of Notch1 by p300 decreases the ubiquitination of Notch1. ► CDK8 inhibits Notch acetylation and Notch transcription enhanced by p300.