Structure of the polycomb group protein PCGF1 in complex with BCOR reveals basis for binding selectivity of PCGF homologs

Structure. 2013 Apr 2;21(4):665-71. doi: 10.1016/j.str.2013.02.013. Epub 2013 Mar 21.


Polycomb-group RING finger homologs (PCGF1, PCGF2, PCGF3, PCGF4, PCGF5, and PCGF6) are critical components in the assembly of distinct Polycomb repression complex 1 (PRC1)-related complexes. Here, we identify a protein interaction domain in BCL6 corepressor, BCOR, which binds the RING finger- and WD40-associated ubiquitin-like (RAWUL) domain of PCGF1 (NSPC1) and PCGF3 but not of PCGF2 (MEL18) or PCGF4 (BMI1). Because of the selective binding, we have named this domain PCGF Ub-like fold discriminator (PUFD). The structure of BCOR PUFD bound to PCGF1 reveals that (1) PUFD binds to the same surfaces as observed for a different Polycomb group RAWUL domain and (2) the ability of PUFD to discriminate among RAWULs stems from the identity of specific residues within these interaction surfaces. These data show the molecular basis for determining the binding preference for a PCGF homolog, which ultimately helps determine the identity of the larger PRC1-like assembly.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Crystallization
  • Humans
  • Models, Molecular*
  • Molecular Sequence Data
  • Multiprotein Complexes / chemistry*
  • Multiprotein Complexes / metabolism
  • Polycomb Repressive Complex 1 / chemistry*
  • Polycomb Repressive Complex 1 / metabolism
  • Protein Conformation*
  • Proto-Oncogene Proteins / chemistry*
  • Proto-Oncogene Proteins / metabolism
  • Repressor Proteins / chemistry*
  • Repressor Proteins / metabolism
  • Sequence Alignment
  • Substrate Specificity
  • Ultracentrifugation


  • BCOR protein, human
  • Multiprotein Complexes
  • PCGF1 protein, human
  • Proto-Oncogene Proteins
  • Repressor Proteins
  • Polycomb Repressive Complex 1

Associated data

  • PDB/4HPM