Structure of the C-terminal region of p21(WAF1/CIP1) complexed with human PCNA

Cell. 1996 Oct 18;87(2):297-306. doi: 10.1016/s0092-8674(00)81347-1.


The crystal structure of the human DNA polymerase delta processivity factor PCNA (proliferating cell nuclear antigen) complexed with a 22 residue peptide derived from the C-terminus of the cell-cycle checkpoint protein p21(WAF1/CIP1) has been determined at 2.6 angstrom resolution. p21 binds to PCNA in a 1:1 stoichiometry with an extensive array of interactions that include the formation of a beta sheet with the interdomain connector loop of PCNA. An intact trimeric ring is maintained in the structure of the p21-PCNA complex, with a central hole available for DNA interaction. The ability of p21 to inhibit the action of PCNA is therefore likely to be due to its masking of elements on PCNA that are required for the binding of other components of the polymerase assembly.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Crystallography, X-Ray
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins / chemistry*
  • Humans
  • Macromolecular Substances
  • Models, Molecular
  • Molecular Sequence Data
  • Proliferating Cell Nuclear Antigen / chemistry*
  • Protein Binding
  • Solubility
  • Solvents
  • Static Electricity
  • Water


  • CDKN1A protein, human
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • Macromolecular Substances
  • Proliferating Cell Nuclear Antigen
  • Solvents
  • Water