Scaffold subunit of various histone acetyltransferase (HAT) complexes, such as the MOZ/MORF and HBO1 complexes, which have a histone H3 acetyltransferase activity (By similarity). Plays a key role in HBO1 complex by directing KAT7/HBO1 specificity towards histone H3 'Lys-14' acetylation (H3K14ac) (By similarity). Some HAT complexes preferentially mediate histone H3 'Lys-23' (H3K23ac) acetylation (PubMed:27939640). Positively regulates the transcription of RUNX1 and RUNX2 (By similarity). Component of some HBO1 complex composed of KAT7/HBO1, MEAF6, ING5, and BRPF1. Component of the MOZ/MORF complex composed at least of ING5, KAT6A, KAT6B, MEAF6 and one of BRPF1, BRD1/BRPF2 and BRPF3. Interacts (via PHD-type zinc finger domains) with unmethylated histone H3 at 'Lys-4' (H3K4me0). Interacts with trimethylated 'Lys-36' of histone H3 (H3K36me3). Interacts with ING5; interaction directs BRPF1 to H4K4me3-enriched chromatin at the 5' of active genes. Interacts with KAT7. Localization to the nucleus depends on KAT6A, ING5 and MEAF6. Localizes to transcription start sites. Expressed at low level in most tissues, with high expression in the testis and specific regions of the brain. Expressed in the placenta, yolk sac, limb buds, brain, spinal cord, retina, nose, bone and brown fat at the prenatal stages. Acetylated by KAT6A. Embryonic lethality around embryonic day 9.5 caused by arrested vasculogenesis in the yolk sac and embryo proper (PubMed:24646517, PubMed:25773539). Embryos also display abnormal neural tube closure (PubMed:25773539).