Scaffold subunit of some HBO1 complexes, which have a histone H4 acetyltransferase activity. Component of the HBO1 complex composed at least of ING4 or ING5, KAT7/HBO1, MEAF6, and one of JADE1, JADE2 and JADE3. Ubiquitously expressed, with highest levels in placenta and uterus. By estradiol in estrogen-responsive breast cancer cells. Belongs to the JADE family.