Plays a role in the inhibition of host immune response within the nucleus. Interacts with cellular nucleosomes and immobilizes the host immune danger signal HMGB1 on chromatin. In turn, prevents HMGB1 release out of the cell and thus decreases inflammation. Also plays a role in the wrapping and condensation of the viral DNA. May also promote viral genome import into the nucleus. Interacts with the core-capsid bridging protein; this interaction bridges the virus core to the capsid. Interacts with host NPM1; this interaction might play a role in placing the pre-histone-like nucleoprotein on the viral DNA or regulating viral gene expression. Interacts with host HMGB1; this interaction inhibits host immune response. Located inside the capsid in association with the viral DNA (core). Present in about 1070 copies per virion. Expressed in the late phase of the viral replicative cycle. Cleaved near the N-terminus by the viral protease during virion maturation to form the mature protein. All late proteins expressed from the major late promoter are produced by alternative splicing and alternative polyadenylation of the same gene giving rise to non-overlapping ORFs. A leader sequence is present in the N-terminus of all these mRNAs and is recognized by the viral shutoff protein to provide expression although conventional translation via ribosome scanning from the cap has been shut off in the host cell. Belongs to the adenoviridae histone-like nucleoprotein family. Extended N-terminus.