Mapping the substrate landscape of protein phosphatase 2A catalytic subunit PPP2CA

Autor: Abigail Brewer, Gajanan Sathe, Billie E. Pflug, Rosemary G. Clarke, Thomas J. Macartney, Gopal P. Sapkota
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: iScience, Vol 27, Iss 3, Pp 109302- (2024)
Druh dokumentu: article
ISSN: 2589-0042
DOI: 10.1016/j.isci.2024.109302
Popis: Summary: Protein phosphatase 2A (PP2A) is an essential Ser/Thr phosphatase. The PP2A holoenzyme complex comprises a scaffolding (A), regulatory (B), and catalytic (C) subunit, with PPP2CA being the principal catalytic subunit. The full scope of PP2A substrates in cells remains to be defined. To address this, we employed dTAG proteolysis-targeting chimeras to efficiently and selectively degrade dTAG-PPP2CA in homozygous knock-in HEK293 cells. Unbiased global phospho-proteomics identified 2,204 proteins with significantly increased phosphorylation upon dTAG-PPP2CA degradation, implicating them as potential PPP2CA substrates. A vast majority of these are novel. Bioinformatic analyses revealed involvement of the potential PPP2CA substrates in spliceosome function, cell cycle, RNA transport, and ubiquitin-mediated proteolysis. We identify a pSP/pTP motif as a predominant target for PPP2CA and confirm some of our phospho-proteomic data with immunoblotting. We provide an in-depth atlas of potential PPP2CA substrates and establish targeted degradation as a robust tool to unveil phosphatase substrates in cells.
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