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The role of p58IPK in protecting the stressed endoplasmic reticulum
Journal article   Open access   Peer reviewed

The role of p58IPK in protecting the stressed endoplasmic reticulum

D Thomas Rutkowski, Sang-Wook Kang, Alan G Goodman, Jennifer L Garrison, Jack Taunton, Michael G Katze, Randal J Kaufman and Ramanujan S Hegde
Molecular biology of the cell, Vol.18(9), pp.3681-3691
09/2007
DOI: 10.1091/mbc.E07-03-0272
PMCID: PMC1951758
PMID: 17567950
url
https://doi.org/10.1091/mbc.E07-03-0272View
Published (Version of record) Open Access

Abstract

The preemptive quality control (pQC) pathway protects cells from acute endoplasmic reticulum (ER) stress by attenuating translocation of nascent proteins despite their targeting to translocons at the ER membrane. Here, we investigate the hypothesis that the DnaJ protein p58(IPK) plays an essential role in this process via HSP70 recruitment to the cytosolic face of translocons for extraction of translocationally attenuated nascent chains. Our analyses revealed that the heightened stress sensitivity of p58-/- cells was not due to an impairment of the pQC pathway or elevated ER substrate burden during acute stress. Instead, the lesion was in the protein processing capacity of the ER lumen, where p58(IPK) was found to normally reside in association with BiP. ER lumenal p58(IPK) could be coimmunoprecipitated with a newly synthesized secretory protein in vitro and stimulated protein maturation upon overexpression in cells. These results identify a previously unanticipated location for p58(IPK) in the ER lumen where its putative function as a cochaperone explains the stress-sensitivity phenotype of knockout cells and mice.
Amino Acid Sequence NIH 3T3 Cells HSP40 Heat-Shock Proteins - metabolism Protein Biosynthesis Molecular Chaperones - metabolism Heat-Shock Proteins - metabolism Humans Molecular Sequence Data HSP40 Heat-Shock Proteins - deficiency Protein Sorting Signals Protein Precursors - metabolism Protein Transport Prolactin - metabolism Endoplasmic Reticulum - pathology Animals Protein Binding Mice HeLa Cells HSP40 Heat-Shock Proteins - chemistry

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