Regulatory subunit of the histone acetylase B (HAT-B) complex. The complex acetylates 'Lys-12' of histone H4 which is required for telomeric silencing. HAT2 is required for high affinity binding of the acetyltransferase to histone H4, for the nuclear location of HAT1 and for the HAT1-HIF1 interaction. Alone, it is unable to bind to H4, requiring HAT1 for high affinity interaction with the histone tail. HAT2 has also a HAT1 independent function in life-span regulation. Component of the HAT-B complex composed of at least HAT1 and HAT2. In the cytoplasm, this complex binds to the histone H4 tail. In the nucleus, the HAT-B complex has an additional component, the histone H3/H4 chaperone HIF1. The nuclear location requires the presence of HAT2. Repressed in presence of farnesol, probably through a intracellular decrease of diacylglycerol. Belongs to the WD repeat RBAP46/RBAP48/MSI1 family.