Scaffold subunit of some HBO1 complexes, which have a histone H4 acetyltransferase activity . Acts as an E3 ubiquitin-protein ligase mediating the ubiquitination and subsequent proteasomal degradation of target protein histone demethylase KDM1A . Also acts as a ubiquitin ligase E3 toward itself. Positive regulator of neurogenesis (By similarity).