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Article
Novel functions of the ER-located Hsp40s DNAJB12 and DNAJB14 on proteins at the outer mitochondrial membrane under stress mediated by CCCP
The endoplasmic reticulum (ER) membrane provides infrastructure for intracellular signaling, protein degradation, and communication among the ER lumen, cytosol, and nucleus via transmembrane and membrane-assoc...
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Chapter
Specification of Hsp70 Function by Hsp40 Co-chaperones
Cellular homeostasis and stress survival requires maintenance of the proteome and suppression of proteotoxicity. Molecular chaperones promote cell survival through repair of misfolded proteins and cooperation ...
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Chapter
Specification of Hsp70 Function by Type I and Type II Hsp40
Cellular homeostasis and stress survival requires maintenance of the proteome and suppression of proteotoxicity. Molecular chaperones promote cell survival through repair of misfolded proteins and cooperation ...
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Article
Open AccessInhibition of post-translational N-glycosylation by HRD1 that controls the fate of ABCG5/8 transporter
N-glycosylation of proteins in endoplasmic reticulum is critical for protein quality control. We showed here a post-translational N-glycosylation affected by the HRD1 E3 ubiquitin ligase. Both WT- and E3-defec...
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Protocol
Cellular Responses to Misfolded Proteins and Protein Aggregates
Maintenance of the proteome is a major homeostatic task of the cell and disregulation of protein homeostasis can be deadly. The accumulation of different forms of misfolded protein can perturb protein homeosta...
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Article
Open AccessCentral domain deletions affect the SAXS solution structure and function of Yeast Hsp40 proteins Sis1 and Ydj1
Ydj1 and Sis1 are structurally and functionally distinct Hsp40 proteins of the yeast cytosol. Sis1 is an essential gene whereas the ydj1 gene is essential for growth at elevated temperatures and cannot complement...
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Protocol
Analysis of CFTR Folding and Degradation in Transiently Transfected Cells
Misfolding and premature degradation of F508del-CFTR is the major cause of cystic fibrosis. Components of the ubiquitin-proteasome system function on the surface of the endoplasmic reticulum to select misfolde...
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Protocol
Reconstitution of CHIP E3 Ubiquitin Ligase Activity
CHIP, the carboxyl-terminus of Hsp70 interacting protein, is both an E3 ubiquitin ligase and an Hsp70 co-chaperone and is implicated in the degradation of cytosolic quality control and numerous disease substra...
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Article
Open AccessThe role of the UPS in cystic fibrosis
CF is an inherited autosomal recessive disease whose lethality arises from malfunction of CFTR, a single chloride (Cl-) ion channel protein. CF patients harbor mutations in the CFTR gene that lead to misfolding o...
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Chapter
Do Hsp40s Act as Chaperones or Co-Chaperones?
The Hsp70 family plays an essential role in cellular protein metabolism by acting as a polypeptide binding and release factor that interacts with nonnative regions of proteins at different stages o...
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Article
CHIP-mediated stress recovery by sequential ubiquitination of substrates and Hsp70
CHIP — a co-chaperone/ubiquitin ligase — not only targets chaperone substrates for degradation, but mediates Hsp70 turnover after misfolded substrates have been depleted. The sequential catalysis of the CHIP-a...
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Article
Arrest of CFTRΔF508 folding
The deletion of residue 508 in CFTR is the most common cystic fibrosis–causing mutation. Recent studies indicate that the main chain and side chain of this residue contribute to the proper folding of CFTR at d...
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Protocol
Cystic Fibrosis Transmembrane Conductance Regulator as a Model Substrate to Study Endoplasmic Reticulum Protein Quality Control in Mammalian Cells
Components of the ubiquitin-proteasome system function on the surface of the endoplasmic reticulum (ER) to select misfolded proteins for degradation. Herein we describe methods that allow for the study of the ...
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Protocol
Isolation of CFTR
The cystic fibrosis transmembrane conductance regulator (CFTR) is a membrane glycoprotein that contains several large cytosolic subdomains. To progress through the secretory pathway, CFTR must fold and assembl...
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Article
The Hsc70 co-chaperone CHIP targets immature CFTR for proteasomal degradation
The folding of both wild-type and mutant forms of the cystic-fibrosis transmembrane-conductance regulator (CFTR), a plasma-membrane chloride-ion channel, is inefficient1,2,3,4. Most nascent CFTR is retained in th...
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Article
Coupling Chemical Energy by the hsp70/tim44 Complex to Drive Protein Translocation into Mitochondria
A dynamic complex between the mitochondrial cognate of hsp70 (mthsp70) and the inner membrane protein tim44 couples energy derived from ATP hydrolysis to drive multiple steps in the mitochondrial protein impor...
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Chapter and Conference Paper
Cytosolic Reactions in Mitochondrial Protein Import
Cytosolic hsp70 molecules are involved in maintenance of pre-proteins in transport competent conformations. Genetic and biochemical studies in procaryotes indicate that hsp70 (DnaK) functionally interacts with...
