A Sephin1-insensitive tripartite holophosphatase dephosphorylates translation initiation factor 2α
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J._Biol._Chem.-2018-Crespillo- ...
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Univ Arizona, Dept Chem & BiochemIssue Date
2018-05-18Keywords
phosphoprotein phosphatase 1 (PP1)eukaryotic initiation factor 2 (eIF2)
enzyme inhibitor
G-actin
proteostasis
guanabenz
integrated stress response
protein synthesis
Sephin1
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Crespillo-Casado, A., Claes, Z., Choy, M. S., Peti, W., Bollen, M., & Ron, D. (2018). A Sephin1-insensitive tripartite holophosphatase dephosphorylates translation initiation factor 2α. J. Biol. Chem. 2018 293: 7766-. doi:10.1074/jbc.RA118.002325Journal
JOURNAL OF BIOLOGICAL CHEMISTRYRights
© 2018 Crespillo-Casado et al. Author's Choice—Final version open access under the terms of the Creative Commons CC-BY license.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
The integrated stress response (ISR) is regulated by kinases that phosphorylate the subunit of translation initiation factor 2 and phosphatases that dephosphorylate it. Genetic and biochemical observations indicate that the eIF2(P)-directed holophosphatase, a therapeutic target in diseases of protein misfolding, is comprised of a regulatory subunit, PPP1R15, and a catalytic subunit, protein phosphatase 1 (PP1). In mammals, there are two isoforms of the regulatory subunit, PPP1R15A and PPP1R15B, with overlapping roles in the essential function of eIF2(P) dephosphorylation. However, conflicting reports have appeared regarding the requirement for an additional co-factor, G-actin, in enabling substrate-specific dephosphorylation by PPP1R15-containing PP1 holoenzymes. An additional concern relates to the sensitivity of the holoenzyme to the [(o-chlorobenzylidene)amino]guanidines Sephin1 or guanabenz, putative small-molecule proteostasis modulators. It has been suggested that the source and method of purification of the PP1 catalytic subunit and the presence or absence of an N-terminal repeat-containing region in the PPP1R15A regulatory subunit might influence the requirement for G-actin and sensitivity of the holoenzyme to inhibitors. We found that eIF2(P) dephosphorylation by PP1 was moderately stimulated by repeat-containing PPP1R15A in an unphysiological low ionic strength buffer, whereas stimulation imparted by the co-presence of PPP1R15A and G-actin was observed under a broad range of conditions, low and physiological ionic strength, regardless of whether the PPP1R15A regulatory subunit had or lacked the N-terminal repeat-containing region and whether it was paired with native PP1 purified from rabbit muscle or recombinant PP1 purified from bacteria. Furthermore, none of the PPP1R15A-containing holophosphatases tested were inhibited by Sephin1 or guanabenz.Note
12 month embargo; published online: 4 April 2018ISSN
0021-92581083-351X
PubMed ID
29618508Version
Final published versionSponsors
Wellcome Trust principal research fellowship [Wellcome 200848/Z/16/Z]; Wellcome Trust strategic award [Wellcome 100140]; National Institute of Health [R01NS091336]; American Diabetes Association Pathway to Stop Diabetes [1-14-ACN-31]; Flemish Concerted Research Action [GOA15/016]Additional Links
http://www.jbc.org/lookup/doi/10.1074/jbc.RA118.002325ae974a485f413a2113503eed53cd6c53
10.1074/jbc.RA118.002325
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Except where otherwise noted, this item's license is described as © 2018 Crespillo-Casado et al. Author's Choice—Final version open access under the terms of the Creative Commons CC-BY license.
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