The structure of the PP2A regulatory subunit B56 gamma: the remaining piece of the PP2A jigsaw puzzle

Proteins. 2009 Jan;74(1):212-21. doi: 10.1002/prot.22150.


The PP2A serine/threonine phosphatase regulates a plethora of cellular processes. In the cell the predominant form of the enzyme is a heterotrimer, formed by a core dimer composed of a catalytic and a scaffolding subunit, which assemble together with one of a range of different regulatory B subunits. Here, we present the first structure of a free non-complexed B subunit, B56 gamma. Comparison with the recent structures of a heterotrimeric complex and the core dimer reveals several significant conformational changes in the interface region between the B56 gamma and the core dimer. These allow for an assembly scheme of the PP2A holoenzyme to be put forth where B56 gamma first complexes with the scaffolding subunit and subsequently binds to the catalytic subunit and this induces the formation of a binding site for the invariant C-terminus of the catalytic subunit that locks in the complex as a last step of assembly.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Catalytic Domain
  • Escherichia coli / genetics
  • Holoenzymes / chemistry
  • Molecular Sequence Data
  • Protein Conformation
  • Protein Multimerization
  • Protein Phosphatase 2 / chemistry*
  • Protein Phosphatase 2 / isolation & purification
  • Protein Subunits / chemistry
  • Sequence Alignment


  • Holoenzymes
  • Protein Subunits
  • Protein Phosphatase 2