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Updated: May 26, 2026

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle
Published on: March 5, 2019
Phosphorylation of the p68 subunit of Pol δ acts as a molecular switch to regulate its interaction with PCNA
Amal A Rahmeh1, Yajing Zhou, Bin Xie
1Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York 10595, United States.
Abstract:
DNA polymerase delta (Pol δ) is a central enzyme for eukaryotic DNA replication and repair. Pol δ is a complex of four subunits p125, p68, p50, and p12. The functional properties of Pol δ are largely determined by its interaction with its DNA sliding clamp PCNA (proliferating cellular nuclear antigen). The regulatory mechanisms that govern the association of Pol δ with PCNA are largely unknown. In this study, we identified S458, located in the PCNA-interacting protein (PIP-Box) motif of p68, as a phosphorylation site for PKA. Phosphomimetic mutation of S458 resulted in a decrease in p68 affinity for PCNA as well as the processivity of Pol δ. Our results suggest a role of phosphorylation of the PIP-motif of p68 as a molecular switch that dynamically regulates the functional properties of Pol δ.
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