CELL-CYCLE-REGULATED PHOSPHORYLATION OF DNA-REPLICATION FACTOR-A FROM HUMAN AND YEAST-CELLS

Replication factor A (RF-A) is a multisubunit, cellular protein that functions with SV40 T antigen during the initiation stage of DNA replication at the SV40 origin. It also cooperates with other replication factors to stimulate the activity of both polymerases α and δ during chain elongation. RF-A from both human and yeast cells is phosphorylated in a cell-cycle-dependent manner; the protein is phosphorylated at the G1- to S-phase transition, and dephosphorylation occurs at mitosis, thereby resetting this cycle. This observation provides a direct link between a protein required for DNA replication and cell-cycle-regulated protein phosphorylation.