Nuclear protein, coactivator of histone transcription (NPAT)

Nuclear protein, coactivator of histone transcription (NPAT) is a pivotal nuclear protein and transcriptional coactivator that integrates cell cycle signals with the activation of histone gene promoters during the G1/S phase transition. It is directly phosphorylated by cyclin E/CDK2 and is essential for the coordinated transcription of replication-dependent histone genes (H2A, H2B, H3, and H4). NPAT achieves this by recruiting coactivator complexes, notably the Tip60 and NuA4 histone acetyltransferase complexes, to histone gene promoters. This role makes it integral to the formation and function of histone locus bodies (HLBs), which organize histone gene expression and 3'-end mRNA processing in the nucleus. NPAT's activity is modulated by phosphorylation and interaction with regulatory partners (such as TRRAP, FLASH, and chaperones), linking cell cycle progression with chromatin structure and genomic stability. Alterations in NPAT have been associated with cell cycle defects, genomic instability, and cancer predisposition, although it is not currently a drug target and no drugs directly modulate NPAT.

Other names

Protein NPATCAND3E14Nuclear protein of the ATM locusp220Nuclear protein of the ataxia-telangiectasia mutated locusE14/NPAT