The human homologue of fission Yeast cdc27, p66, is a component of active human DNA polymerase delta

J Biochem. 2001 May;129(5):699-708. doi: 10.1093/oxfordjournals.jbchem.a002909.


An essential eukaryotic DNA polymerase, DNA polymerase delta (pol delta), synthesizes DNA processively in the presence of proliferating cell nuclear antigen (PCNA). Recently, a 66 kDa polypeptide (p66) that displays significant homology within its PCNA binding domain to that of fission yeast cdc27 was identified as a component of mouse and calf thymus pol delta. Our studies show that p66 interacts tightly with other subunits of pol delta during size fractionation of human cell extracts, and co-immunoprecipitates with these subunits along with PCNA-dependent polymerase activity. Active human pol delta could be reconstituted by co-expressing p125, p50, and p66 recombinant baculoviruses, but not by co-expressing p125 and p50 alone. Interaction studies demonstrated that p66 stabilizes the association between p125 and p50. Pull-down assays with PCNA-linked beads demonstrated that p66 increases the overall affinity of pol delta for PCNA. These results indicate that p66 is a functionally important subunit of human pol delta that stabilizes the pol delta complex and increases the affinity of pol delta for PCNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome
  • Cattle
  • Cell Cycle Proteins / chemistry*
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • DNA Polymerase III / chemistry*
  • DNA Polymerase III / genetics
  • DNA Polymerase III / metabolism*
  • Enzyme Stability / physiology
  • Humans
  • Mice
  • Mice, Inbred BALB C
  • Peptides / chemistry*
  • Peptides / genetics
  • Proliferating Cell Nuclear Antigen / chemistry*
  • Proliferating Cell Nuclear Antigen / metabolism
  • Protein Subunits
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Schizosaccharomyces / chemistry
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces pombe Proteins
  • Sequence Homology


  • Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome
  • CDC27 protein, human
  • Cell Cycle Proteins
  • Peptides
  • Proliferating Cell Nuclear Antigen
  • Protein Subunits
  • Recombinant Proteins
  • Schizosaccharomyces pombe Proteins
  • cdc27 protein, S pombe
  • POLD3 protein, human
  • DNA Polymerase III