Behaviour of intrinsically disordered proteins in protein-protein complexes with an emphasis on fuzziness

Cell Mol Life Sci. 2017 Sep;74(17):3175-3183. doi: 10.1007/s00018-017-2560-7. Epub 2017 Jun 8.


Intrinsically disordered proteins (IDPs) do not, by themselves, fold into a compact globular structure. They are extremely dynamic and flexible, and are typically involved in signalling and transduction of information through binding to other macromolecules. The reason for their existence may lie in their malleability, which enables them to bind several different partners with high specificity. In addition, their interactions with other macromolecules can be regulated by a variable amount of chemically diverse post-translational modifications. Four kinetically and energetically different types of complexes between an IDP and another macromolecule are reviewed: (1) simple two-state binding involving a single binding site, (2) avidity, (3) allovalency and (4) fuzzy binding; the last three involving more than one site. Finally, a qualitative definition of fuzzy binding is suggested, examples are provided, and its distinction to allovalency and avidity is highlighted and discussed.

Keywords: Allovalency; Avidity; Disorder; Fuzzy complex; IDP; Kinetics; Signalling.

Publication types

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

MeSH terms

  • Animals
  • Clathrin / chemistry
  • Clathrin / metabolism
  • Humans
  • Intrinsically Disordered Proteins / chemistry
  • Intrinsically Disordered Proteins / metabolism*
  • Kinetics
  • Models, Molecular
  • Monomeric Clathrin Assembly Proteins / chemistry
  • Monomeric Clathrin Assembly Proteins / metabolism
  • Nuclear Pore Complex Proteins / chemistry
  • Nuclear Pore Complex Proteins / metabolism
  • Nucleocytoplasmic Transport Proteins / chemistry
  • Nucleocytoplasmic Transport Proteins / metabolism
  • Protein Binding
  • Protein Processing, Post-Translational


  • Clathrin
  • Intrinsically Disordered Proteins
  • Monomeric Clathrin Assembly Proteins
  • Nuclear Pore Complex Proteins
  • Nucleocytoplasmic Transport Proteins
  • clathrin assembly protein AP180