DNA Polymerase delta tetramer RNA primer-DNA primer:origin duplex:PCNA Processive complex Processive synthesis on the leading strand Polymerase switching is a key event that allows the processive synthesis of DNA by the pol delta and PCNA complex. Polymerase delta possesses polymerization and proofreading activities, which increases the overall fidelity of DNA replication. The pol delta holoenzyme is a heterotetrameric complex that contains p125, p66, p50, and p12 subunits, in human cells. Pubmed10751307 Pubmed1671046 Pubmed7378348 Pubmed9191022 Reactome Database ID Release 4369098 Reactome, http://www.reactome.org ReactomeREACT_149