As a component of the TREX-2 complex, involved in the export of mRNAs to the cytoplasm through the nuclear pores (PubMed:20005110, PubMed:20384790, PubMed:23591820, PubMed:22307388). Through the acetylation of histones, affects the assembly of nucleosomes at immunoglobulin variable region genes and promotes the recruitment and positioning of transcription complex to favor DNA cytosine deaminase AICDA/AID targeting, hence promoting somatic hypermutations (PubMed:23652018). Binds to and acetylates the replication protein MCM3. Plays a role in the initiation of DNA replication and participates in controls that ensure that DNA replication initiates only once per cell cycle (PubMed:11258703, PubMed:12226073). Through the acetylation of histones, affects the assembly of nucleosomes at immunoglobulin variable region genes and promotes the recruitment and positioning of transcription complex to favor DNA cytosine deaminase AICDA/AID targeting, hence promoting somatic hypermutations (PubMed:23652018). acetyl-CoA + L-lysyl-[histone] = CoA + H(+) + N(6)-acetyl-L-lysyl-[histone] Isoform GANP: Component of the nuclear pore complex (NPC)-associated TREX-2 complex (transcription and export complex 2), composed of at least GANP, 2 copies of ENY2, PCID2, SEM1/DSS1, and either centrin CETN2 or centrin CETN3. The TREX-2 complex also associates with ALYREF/ALY (PubMed:23591820, PubMed:22307388). Interacts with RNA polymerase II subunit POLR2A and with the transcription elongation factor SUPT5H/SPT5 (PubMed:23652018, PubMed:22307388). Interacts (via FG-repeats) with NXF1; this interaction is not mediated by RNA (PubMed:20005110). Isoform GANP interacts with nuclear envelope proteins NUP62, NUP153 and RANBP2/NUP358; interaction with NUP153 is required for full localization at the nuclear pore complex (PubMed:20005110, PubMed:23652018). Interacts with several RNA helicases, including DHX9, DDX21, and DDX39A/DDX39, and with DNA topoisomerase TOP2A (PubMed:23652018). Directly interacts with AICDA/AID (PubMed:20507984). Interacts with the glucocorticoid receptor NR3C1 (PubMed:16914116). Isoform MCM3AP: Interacts with the glucocorticoid receptor NR3C1 (PubMed:16914116). Interacts with MCM3; this interaction leads to MCM3 acetylation (PubMed:9712829, PubMed:11258703, PubMed:12226073). Predominantly located at the nuclear envelope, facing the nucleus interior (PubMed:20005110, PubMed:21195085, PubMed:23591820). Localization at the nuclear pore complex requires NUP153, TPR and ALYREF/ALY (PubMed:23591820, PubMed:22307388). Also found associated with chromatin (PubMed:23652018). In B-cells, targeted to the immunoglobulin variable region genes (PubMed:23652018). Translocates into the nucleus in the presence of MCM3 (PubMed:12226073). Associates with chromatin possibly through interaction with MCM3 (PubMed:12226073). Widely expressed (PubMed:11024281). Up-regulated in germinal center B-cells in tonsils (at protein level) (PubMed:11024281). The disease is caused by variants affecting distinct genetic loci, including the gene represented in this entry. Produced via an alternative promoter within an intron of GANP. MCM3AP promoter elements are poorly conserved in mice, suggesting that the regulation of MCM3AP may be human specific. Belongs to the SAC3 family.