May modulate chromatin structure by regulation of nucleosome assembly/disassembly (By similarity). May function in nucleotide excision repair (NER). Involved in somatic homologous recombination. Can form homomeric and heteromeric protein complexes with NAP1;1, NAP1;3 and NAP1;4. Binds histone H2A. Predominantly located in cytoplasm. A number of isoforms are produced. According to EST sequences. Ubiquitous. By brassinosteroids. The acidic domain is probably involved in the interaction with histones. No visible phenotype. Triple mutant nap1;1-nap1;2-nap1;3 has no obvious visible phenotype but exhibits hypersensitivity to DNA damage after UV-radiation, affected transcription of NER related genes (PubMed:19228338), slight hypersensitive response to abscisic acid (ABA) in seedling growth (PubMed:19825649) and impaired somatic homologous recombination (PubMed:22534127). Belongs to the nucleosome assembly protein (NAP) family.