Scaffold subunit of some HBO1 complexes, which have a histone H4 acetyltransferase activity (PubMed:16387653, PubMed:19187766, PubMed:20129055, PubMed:24065767). Plays a key role in HBO1 complex by directing KAT7/HBO1 specificity towards histone H4 acetylation (H4K5ac, H4K8ac and H4K12ac), regulating DNA replication initiation, regulating DNA replication initiation (PubMed:20129055, PubMed:24065767). May also promote acetylation of nucleosomal histone H4 by KAT5 (PubMed:15502158). Promotes apoptosis (PubMed:16046545). May act as a renal tumor suppressor (PubMed:16046545). Negatively regulates canonical Wnt signaling; at least in part, cooperates with NPHP4 in this function (PubMed:22654112). {ECO:0000269|PubMed:15502158, ECO:0000269|PubMed:16046545, ECO:0000269|PubMed:16387653, ECO:0000269|PubMed:19187766, ECO:0000269|PubMed:20129055, ECO:0000269|PubMed:22654112, ECO:0000269|PubMed:24065767}. This is the function of Ensembl gene identifier ENSG00000077684 (JADE1, jade family PHD finger 1).