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The structure of the PP2A regulatory subunit B56gamma: The remaining piece of the PP2A jigsaw puzzle
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
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2009 (English)In: Proteins: Structure, Function, and Genetics, ISSN 0887-3585, E-ISSN 1097-0134, Vol. 74, no 1, 212-221 p.Article in journal (Refereed) Published
Abstract [en]

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. 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 and the core dimer. These allow for an assembly scheme of the PP2A holoenzyme to be put forth where B56 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.

Place, publisher, year, edition, pages
2009. Vol. 74, no 1, 212-221 p.
Keyword [en]
crystal structure, holoenzyme assembly, PP2A regulation, PR61, B56, B regulatory subunits, protein phosphatase
National Category
Biochemistry and Molecular Biology
URN: urn:nbn:se:su:diva-25541DOI: 10.1002/prot.22150ISI: 000261757900019OAI: diva2:199928
Available from: 2008-10-23 Created: 2008-10-14 Last updated: 2011-05-20Bibliographically approved
In thesis
1. Structural Studies on PP2A and Methods in Protein Production
Open this publication in new window or tab >>Structural Studies on PP2A and Methods in Protein Production
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

PP2A is a major phosphatase in the cell that participates in multiple cell signaling pathways. It is a heterotrimer of a core dimer and variable regulatory subunits. Details of its structure, function and regulation are slowly emerging. Here, the structure of two regulators of PP2A are de-scribed; PTPA and B56γ. PTPA is a highly conserved enzyme that plays a crucial role in PP2A activity but whose biochemical function is still unclear. B56γ is a PP2A regulatory subunit linked to cancer and the structure presented here of B56γ in its free form is particularly valuable in light of the recent structures of the PP2A holoenzyme and core dimer.

Protein production is a major bottleneck in structural genomic projects. Here, we describe two novel methods for improved protein production. The first is a colony based screening method where any DNA library can be screened for soluble expression of recombinant proteins in E.coli. The second method involves improvements of the well established IMAC purification method. We have seen that a low molecular weight component of E.coli lysate decreases the binding capacity of IMAC columns and by removing the low molecular weight components, recombinant proteins only present at low levels in E.coli lysate can be purified, which has previously been believed to be unfeasible.

Place, publisher, year, edition, pages
Stockholm: Institutionen för biokemi och biofysik, 2008. 53 p.
PP2A, PTPA, B56γ, Protein Production
National Category
Structural Biology
Research subject
urn:nbn:se:su:diva-8261 (URN)978-91-7155-750 (ISBN)
Public defence
2008-11-14, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 10:00
Available from: 2008-10-23 Created: 2008-10-14Bibliographically approved

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