Chromatin Assembly Factor 1, Subunit A (p150)

Chromatin assembly factor 1 (CAF-1) is a histone H3/H4 chaperone complex that functions in de novo assembly of nucleosomes during DNA replication and nucleotide excision repair (1). Nucleosome assembly is a two-step process, involving initial deposition of a histone H3/H4 tetramer onto DNA, followed by the deposition of a pair of histone H2A/H2B dimers (1). CAF-1 interacts with PCNA and localizes to DNA replication and DNA repair foci, where it functions to assemble newly synthesized histone H3/H4 tetramers onto replicating DNA (2-6). Assembly of histone H2A/H2B dimers requires additional assembly factors. The CAF-1 complex consists of three proteins: CHAF1A (p150), CHAF1B (p60) and RBAP48 (p48 or RBBP4). CHAF1A and CHAF1B proteins are specific for the CAF-1 complex, while RBAP48 is a component of multiple chromatin modifying complexes (1). CHAF1A and CHAF1B expression levels correlate with cellular proliferation and both proteins are significantly down-regulated in quiescent cells (7).