HIRIP3 (HIRA interacting protein 3) functions as a histone chaperone that specifically carries H2A-H2B histone dimers and facilitates their deposition onto chr16 1. The protein acts as an H2A histone chaperone, physically interacting with the H2A αC helix through an extended CHZ domain and playing a crucial role in depositing canonical core histones onto naked DNA 1. HIRIP3 is associated in vivo with H2A-H2B dimers and CK2 kinase, which shows preference for H2A phosphorylation at serine 1 1. Originally identified through its interaction with the HIRA histone chaperone, HIRIP3 directly interacts with core histones H2B and H3, suggesting it functions as part of a HIRA-HIRIP3-containing complex involved in chr16 and histone metabolism 2. The protein is nuclear throughout the cell cycle, excluded from condensed chr16 during mitosis, and is heavily phosphorylated by CK2 kinase 3. HIRIP3 expression is regulated through sense/antisense interactions with the overlapping INO80E gene, forming RNA:RNA duplexes that stabilize mRNAs 4. The gene is expressed in neural progenitors during human fetal cerebral cortex development and has been identified as a potential diagnostic biomarker in Alzheimer's disease 56.