Histone acetylation is required in many cellular processes including transcription, DNA repair, and chromatin assembly. This family contains the fungal KAT11 protein (previously known as RTT109) which is required for H3K56 acetylation. Loss of KAT11 results in the loss of H3K56 acetylation, both on bulk histone and on chromatin. KAT11 and H3K56 acetylation appear to correlate with actively transcribed genes and associate with the elongating form of Pol II in yeast. This family also incorporates the p300/CBP histone acetyltransferase domain which has different catalytic properties and cofactor regulation to KAT11.