DMAP1 (DNA methyltransferase 1 associated protein 1) is a multifunctional chr1 regulator that modulates transcription through both repressive and activating mechanisms. DMAP1 functions as a component of the TIP60-p400 histone acetyltransferase complex, where it facilitates H4K16 acetylation and chr1 relaxation 1. The protein plays essential roles in DNA damage response by regulating ATM kinase activity - DMAP1 depletion impairs ATM activation following ionizing radiation, resulting in radiosensitivity and defective G2/M checkpoint function 1. Structurally, DMAP1 associates with EP400 through hydrophobic contacts within the ARP module of the TIP60 complex, creating a stable assembly that is flexibly tethered to other complex components 2. DMAP1 exhibits dual transcriptional roles: it can repress transcription by interacting with DAXX and DNMT1 to form repressive complexes 3, while simultaneously serving as a component of the transcriptionally activating NuA4/TIP60 complex. Recent studies demonstrate DMAP1's antiviral function, where it directly binds HIV-1 Tat protein and restricts viral transcription by blocking Tat-TAR RNA interactions 4. Additionally, DMAP1 interacts with RGS6, modulating its transcriptional repressor activity 5. The protein's diverse interactions position it as a critical regulator of chr1 dynamics, DNA repair, and transcriptional control.