Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Review Article
  • Published:

Retro-translocation of proteins from the endoplasmic reticulum into the cytosol

Nature Reviews Molecular Cell Biology volume 3, pages 246–255 (2002)Cite this article

Key Points

  • When newly synthesized proteins translocate into the endoplasmic reticulum (ER) lumen, they undergo 'quality control'. An elaborate system of chaperones helps proteins to fold and prevents misfolded polypeptides from reaching their final destination.

  • ; Misfolded proteins that cannot be brought back to their native state are degraded. Recent evidence indicates that misfolded proteins are retro-translocated from the ER lumen to the cytosol and are then degraded by the ubiquitin–proteasome system.

  • The retro-translocation pathway is co-opted by certain viruses to degrade proteins that are involved in the immunoprotection of the host. It is also used by some plant and bacterial toxins to enter the cytosol of cells.

  • ; The first step in retro-translocation is the recognition of a misfolded substrate. Exposure of hydrophobic polypeptide patches might represent the general recognition signal and ER chaperones might be the signal receptors. An important player seems to be protein disulphide isomerase and its relatives. BiP and other chaperones have also been implicated in targeting misfolded substrates for retro-translocation.

  • The next step in retro-translocation is the transport of the polypeptide chain across the ER membrane. On the basis of biochemical and genetic data, transport of the polypeptide seems to occur through the protein-conducting channel that is formed by the Sec61 complex. Given the size limitation of the Sec61 channel, it is likely that substrates need to be at least partially unfolded before they can pass through the channel.

  • Polypeptide substrates that emerge from the translocation channel are polyubiquitylated at the membrane. The ubiquitylation machinery comprises both specific conjugation and ligase enzymes. However, polyubiquitylation alone is insufficient to release a substrate into the cytosol.

  • Recent experiments indicate a role for a member of the AAA family of ATPases — Cdc48 in yeast and p97 in mammals — in extracting polypeptides from the ER membrane. These ATPases might 'pull' polypeptides out of the membrane in a similar manner to AAA proteases, which remove misfolded membrane proteins in bacteria and mitochondria.

Abstract

Proteins that are misfolded in the endoplasmic reticulum are transported back into the cytosol for destruction by the proteasome. This retro-translocation pathway has been co-opted by certain viruses, and by plant and bacterial toxins. The mechanism of retro-translocation is still mysterious, but several aspects of this process are now being unravelled.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Pathway of retro-translocation.
Figure 2: Timing mechanism for glycoprotein degradation.
Figure 3: Different modes of translocation.
Figure 4: Extraction of proteins from membranes by AAA ATPases.

Similar content being viewed by others

References

  1. Matlack, K. E. S., Mothes, W. & Rapoport, T. A. Protein translocation — tunnel vision. Cell 92, 381–390 (1998).

    Article  CAS  PubMed  Google Scholar 

  2. Mori, K. Tripartite management of unfolded proteins in the endoplasmic reticulum. Cell 101, 451–454 (2000).

    CAS  PubMed  Google Scholar 

  3. Travers, K. J. et al. Functional and genomic analyses reveal an essential coordination between the unfolded protein response and ER-associated degradation. Cell 101, 249–258 (2000).

    CAS  PubMed  Google Scholar 

  4. Casagrande, R. et al. Degradation of proteins from the ER of S. cerevisiae requires an intact unfolded protein response pathway. Mol. Cell 5, 729–735 (2000).

    CAS  PubMed  Google Scholar 

  5. Friedlander, R., Jarosch, E., Urban, J., Volkwein, C. & Sommer, T. A regulatory link between ER-associated protein degradation and the unfolded-protein response. Nature Cell Biol. 2, 379–384 (2000).

    CAS  PubMed  Google Scholar 

  6. Hong, E., Davidson, A. R. & Kaiser, C. A. A pathway for targeting soluble misfolded proteins to the yeast vacuole. J. Cell Biol. 135, 623–633 (1996).

    CAS  PubMed  Google Scholar 

  7. Chang, A. & Fink, G. R. Targeting of the yeast plasma membrane [H+]ATPase: a novel gene AST1 prevents mislocalization of mutant ATPase to the vacuole. J. Cell Biol. 128, 39–49 (1995).

    CAS  PubMed  Google Scholar 

  8. Klausner, R. D. & Sitia, R. Protein degradation in the endoplasmic reticulum. Cell 62, 611–614 (1990).

    CAS  PubMed  Google Scholar 

  9. Kopito, R. R. ER quality control: the cytoplasmic connection. Cell 88, 427–430 (1997).

    CAS  PubMed  Google Scholar 

  10. McCracken, A. A. & Brodsky, J. L. Assembly of ER-associated protein degradation in vitro: dependence on cytosol, calnexin, and ATP. J. Cell Biol. 132, 291–298 (1996).This report and reference 74 describe in vitro systems for the degradation of ER-associated proteins. Reference 10 first showed a cytosolic requirement for the degradation of a soluble ER protein.

    CAS  PubMed  Google Scholar 

  11. Brodsky, J. L. & McCracken, A. A. ER protein quality control and proteasome-mediated protein degradation. Semin. Cell Dev. Biol. 10, 507–513 (1999).This review gives a list of ER-associated degradation substrates in yeast. Components that are required and not required for their degradation are listed. The table indicates that different degradation pathways exist.

    CAS  PubMed  Google Scholar 

  12. Russell, W. An address on a characteristic organism of cancer. BMJ 2, 1356–1360 (1890).

    CAS  PubMed  PubMed Central  Google Scholar 

  13. Kopito, R. R. & Sitia, R. Aggresomes and Russell bodies. Symptoms of cellular indigestion? EMBO Rep. 1, 225–231 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  14. Rivera, V. M. et al. Regulation of protein secretion through controlled aggregation in the endoplasmic reticulum. Science 287, 826–830 (2000).

    CAS  PubMed  Google Scholar 

  15. Braakman, I., Helenius, J. & Helenius, A. Role of ATP and disulphide bonds during protein folding in the endoplasmic reticulum. Nature 356, 260–262 (1992).

    CAS  PubMed  Google Scholar 

  16. Vashist, S. et al. Distinct retrieval and retention mechanisms are required for the quality control of endoplasmic reticulum protein folding. J. Cell Biol. 155, 355–368 (2001).This paper and reference 17 show that soluble, misfolded ER proteins must first be transported from the ER to the Golgi before they can be degraded.

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Caldwell, S. R., Hill, K. J. & Cooper, A. A. Degradation of endoplasmic reticulum (ER) quality control substrates requires transport between the ER and Golgi. J. Biol. Chem. 276, 23296–23303 (2001).

    CAS  PubMed  Google Scholar 

  18. Kamhi-Nesher, S. et al. A novel quality control compartment derived from the endoplasmic reticulum. Mol. Biol. Cell 12, 1711–1723 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  19. Wiertz, E. J. H. J. et al. The human cytomegalovirus US11 gene product dislocates MHC class I heavy chains from the endoplasmic reticulum to the cytosol. Cell 84, 769–779 (1996).

    CAS  PubMed  Google Scholar 

  20. Wiertz, E. J. H. J. et al. Sec61-mediated transfer of a membrane protein from the endoplasmic reticulum to the proteasome for destruction. Nature 384, 432–438 (1996).This paper provides the first evidence that the Sec61 channel might be involved in retro-translocation of ER proteins. It also shows that viruses can co-opt the cellular pathway.

    CAS  PubMed  Google Scholar 

  21. Schubert, U. et al. CD4 glycoprotein degradation induced by human immunodeficiency virus type 1 Vpu protein requires the function of proteasomes and the ubiquitin-conjugating pathway. J. Virol. 72, 2280–2288 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  22. Boname, J. M. & Stevenson, P. G. MHC class I ubiquitination by a viral phd/lap finger protein. Immunity 15, 627–636 (2001).

    CAS  PubMed  Google Scholar 

  23. Sandvig, K. & van Deurs, B. Entry of ricin and Shiga toxin into cells: molecular mechanisms and medical perspectives. EMBO J. 19, 5943–5950 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  24. Lord, J. M. & Roberts, L. M. Toxin entry: retrograde transport through the secretory pathway. J. Cell Biol. 140, 733–736 (1998).

    CAS  PubMed  Google Scholar 

  25. Lencer, W. I., Hirst, T. R. & Holmes, R. K. Membrane traffic and the cellular uptake of cholera toxin. Biochim. Biophys. Acta 1450, 177–190 (1999).

    CAS  PubMed  Google Scholar 

  26. Schmitz, A., Herrgen, H., Winkeler, A. & Herzog, V. Cholera toxin is exported from microsomes by the Sec61p complex. J. Cell Biol. 148, 1203–1212 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  27. Ellgaard, L. & Helenius, A. ER quality control: towards an understanding at the molecular level. Curr. Opin. Cell Biol. 13, 431–437 (2001).This review summarizes the current knowledge of quality control in the ER, with emphasis on the ER retention and degradation of glycoproteins.

    CAS  PubMed  Google Scholar 

  28. Knop, M., Hauser, N. & Wolf, D. H. N-Glycosylation affects endoplasmic reticulum degradation of a mutated derivative of carboxypeptidase yscY in yeast. Yeast 12, 1229–1238 (1996).

    CAS  PubMed  Google Scholar 

  29. Jakob, C. A., Burda, P., Roth, J. & Aebi, M. Degradation of misfolded endoplasmic reticulum glycoproteins in Saccharomyces cerevisiae is determined by a specific oligosaccharide structure. J. Cell Biol. 142, 1223–1233 (1998).This paper and reference 30 indicate that the generation of a Man8-containing carbohydrate chain targets a misfolded glycoprotein to the degradation machinery.

    CAS  PubMed  PubMed Central  Google Scholar 

  30. Liu, Y., Choudhury, P., Cabral, C. M. & Sifers, R. N. Oligosaccharide modification in the early secretory pathway directs the selection of a misfolded glycoprotein for degradation by the proteasome. J. Biol. Chem. 274, 5861–5867 (1999).

    CAS  PubMed  Google Scholar 

  31. Hosokawa, N. et al. A novel ER α-mannosidase-like protein accelerates ER-associated degradation. EMBO Rep. 2, 415–422 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  32. Nakatsukasa, K., Nishikawa, S., Hosokawa, N., Nagata, K. & Endo, T. Mnl1p, an α-mannosidase-like protein in yeast Saccharomyces cerevisiae, is required for endoplasmic reticulum-associated degradation of glycoproteins. J. Biol. Chem. 276, 8635–8638 (2001).

    CAS  PubMed  Google Scholar 

  33. Jakob, C. A. et al. Htm1p, a mannosidase-like protein, is involved in glycoprotein degradation in yeast. EMBO Rep. 2, 423–430 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  34. Tokunaga, F., Brostrom, C., Koide, T. & Arvan, P. Endoplasmic reticulum (ER)-associated degradation of misfolded N-linked glycoproteins is suppressed upon inhibition of ER mannosidase I. J. Biol. Chem. 275, 40757–40764 (2000).

    CAS  PubMed  Google Scholar 

  35. Wilson, C. M., Farmery, M. R. & Bulleid, N. J. Pivotal role of calnexin and mannose trimming in regulating the endoplasmic reticulum-associated degradation of major histocompatibility complex class I heavy chain. J. Biol. Chem. 275, 21224–21232 (2000).

    CAS  PubMed  Google Scholar 

  36. Gillece, P., Luz, J. M., Lennarz, W. J., de La Cruz, F. J. & Romisch, K. Export of a cysteine-free misfolded secretory protein from the endoplasmic reticulum for degradation requires interaction with protein disulfide isomerase. J. Cell. Biol. 147, 1443–1456 (1999).This paper, and references 40 and 41 , raise the possibility that PDI and related proteins could serve to unfold proteins in the ER lumen and to target substrates to the retro-translocation machinery.

    CAS  PubMed  PubMed Central  Google Scholar 

  37. Fagioli, C., Mezghrani, A. & Sitia, R. Reduction of interchain disulfide bonds precedes the dislocation of Ig-μ chains from the endoplasmic reticulum to the cytosol for proteasomal degradation. J. Biol. Chem. 276, 40962–40967 (2001).

    CAS  PubMed  Google Scholar 

  38. Orlandi, P. A. Protein-disulfide isomerase-mediated reduction of the A subunit of cholera toxin in a human intestinal cell line. J. Biol. Chem. 272, 4591–4599 (1997).

    CAS  PubMed  Google Scholar 

  39. Tortorella, D. et al. Dislocation of type I membrane proteins from the ER to the cytosol is sensitive to changes in redox potential. J. Cell Biol. 142, 365–376 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  40. Wang, Q. & Chang, A. Eps1, a novel PDI-related protein involved in ER quality control in yeast. EMBO J. 18, 5972–5982 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  41. Tsai, B., Rodighiero, C., Lencer, W. I. & Rapoport, T. A. Protein disulfide isomerase acts as a redox-dependent chaperone to unfold cholera toxin. Cell 104, 937–948 (2001).

    CAS  PubMed  Google Scholar 

  42. Knittler, M. R., Dirks, S. & Haas, I. G. Molecular chaperones involved in protein degradation in the endoplasmic reticulum: quantitative interaction of the heat shock cognate protein BiP with partially folded immunoglobulin light chains that are degraded in the endoplasmic reticulum. Proc. Natl Acad. Sci. USA 92, 1764–1768 (1995).

    CAS  PubMed  PubMed Central  Google Scholar 

  43. Plemper, R. K., Bohmler, S., Bordallo, J., Sommer, T. & Wolf, D. H. Mutant analysis links the translocon and BiP to retrograde protein transport for ER degradation. Nature 388, 891–895 (1997).

    CAS  PubMed  Google Scholar 

  44. Brodsky, J. L. et al. The requirement for molecular chaperones during endoplasmic reticulum-associated protein degradation demonstrates that protein export and import are mechanistically distinct. J. Biol. Chem. 274, 3453–3460 (1999).

    CAS  PubMed  Google Scholar 

  45. Matlack, K. E., Misselwitz, B., Plath, K. & Rapoport, T. A. BiP acts as a molecular ratchet during posttranslational transport of prepro-α-factor across the ER membrane. Cell 97, 553–564 (1999).

    CAS  PubMed  Google Scholar 

  46. Chillaron, J. & Haas, I. G. Dissociation from BiP and retrotranslocation of unassembled immunoglobulin light chains are tightly coupled to proteasome activity. Mol. Biol. Cell 11, 217–226 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  47. Misselwitz, B., Staeck, O. & Rapoport, T. A. J proteins catalytically activate Hsp70 molecules to trap a wide range of peptide sequences. Mol. Cell 2, 593–603 (1998).

    CAS  PubMed  Google Scholar 

  48. Gillece, P., Pilon, M. & Romisch, K. The protein translocation channel mediates glycopeptide export across the endoplasmic reticulum membrane. Proc. Natl Acad. Sci. USA 97, 4609–4614 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  49. Pilon, M., Schekman, R. & Romisch, K. Sec61p mediates export of a misfolded secretory protein from the endoplasmic reticulum to the cytosol for degradation. EMBO J. 16, 4540–4548 (1997).

    CAS  PubMed  PubMed Central  Google Scholar 

  50. Nishikawa, S. I., Fewell, S. W., Kato, Y., Brodsky, J. L. & Endo, T. Molecular chaperones in the yeast endoplasmic reticulum maintain the solubility of proteins for retrotranslocation and degradation. J. Cell Biol. 153, 1061–1070 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  51. Chen, Y., Le Caherec, F. & Chuck, S. L. Calnexin and other factors that alter translocation affect the rapid binding of ubiquitin to apoB in the Sec61 complex. J. Biol. Chem. 273, 11887–11894 (1998).

    CAS  PubMed  Google Scholar 

  52. Gewurz, B. E. et al. Antigen presentation subverted: structure of the human cytomegalovirus protein US2 bound to the class I molecule HLA-A2. Proc. Natl Acad. Sci. USA 98, 6794–6799 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  53. Bebok, Z., Mazzochi, C., King, S. A., Hong, J. S. & Sorscher, E. J. The mechanism underlying cystic fibrosis transmembrane conductance regulator transport from the endoplasmic reticulum to the proteasome includes Sec61beta and a cytosolic, deglycosylated intermediary. J. Biol. Chem. 273, 29873–29878 (1998).

    CAS  PubMed  Google Scholar 

  54. de Virgilio, M., Weninger, H. & Ivessa, N. E. Ubiquitination is required for the retro-translocation of a short-lived luminal endoplasmic reticulum glycoprotein to the cytosol for degradation by the proteasome. J. Biol. Chem. 273, 9734–9743 (1998).

    CAS  PubMed  Google Scholar 

  55. Petaja-Repo, U. E. et al. Newly synthesized human δ-opioid receptors retained in the endoplasmic reticulum are retrotranslocated to the cytosol, deglycosylated, ubiquitinated, and degraded by the proteasome. J. Biol. Chem. 276, 4416–4423 (2001).

    CAS  PubMed  Google Scholar 

  56. Wesche, J., Rapak, A. & Olsnes, S. Dependence of ricin toxicity on translocation of the toxin A-chain from the endoplasmic reticulum to the cytosol. J. Biol. Chem. 274, 34443–34449 (1999).

    CAS  PubMed  Google Scholar 

  57. Simpson, J. C. et al. Ricin A chain utilises the endoplasmic reticulum-associated protein degradation pathway to enter the cytosol of yeast. FEBS Lett. 459, 80–84 (1999).

    CAS  PubMed  Google Scholar 

  58. Zhou, M. & Schekman, R. The engagement of Sec61p in the ER dislocation process. Mol. Cell 4, 925–934 (1999).

    CAS  PubMed  Google Scholar 

  59. Walter, J., Urban, J., Volkwein, C. & Sommer, T. Sec61p-independent degradation of the tail-anchored ER membrane protein Ubc6p. EMBO J. 20, 3124–3131 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  60. Kihara, A., Akiyama, Y. & Ito, K. Dislocation of membrane proteins in FtsH-mediated proteolysis. EMBO J. 18, 2970–2981 (1999).This paper and reference 61 show that misfolded proteins are extracted from bacterial and mitochondrial membranes by AAA proteases.

    CAS  PubMed  PubMed Central  Google Scholar 

  61. Leonhard, K. et al. Membrane protein degradation by AAA proteases in mitochondria: extraction of substrates from either membrane surface. Mol. Cell 5, 629–638 (2000).

    CAS  PubMed  Google Scholar 

  62. Hamman, B. D., Chen, J. C., Johnson, E. E. & Johnson, A. E. The aqueous pore through the translocon has a diameter of 40–60 Å during cotranslational protein translocation at the ER membrane. Cell 89, 535–544 (1997).

    CAS  PubMed  Google Scholar 

  63. Menetret, J. et al. The structure of ribosome-channel complexes engaged in protein translocation. Mol. Cell 6, 1219–1232 (2000).

    CAS  PubMed  Google Scholar 

  64. Beckmann, R. et al. Architecture of the protein-conducting channel associated with the translating 80S ribosome. Cell 107, 361–372 (2001).

    CAS  PubMed  Google Scholar 

  65. Mitchell, D. M. et al. Apoprotein B100 has a prolonged interaction with the translocon during which its lipidation and translocation change from dependence on the microsomal triglyceride transfer protein to independence. Proc. Natl Acad. Sci. USA 95, 14733–14738 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  66. Plemper, R. K., Deak, P. M., Otto, R. T. & Wolf, D. H. Re-entering the translocon from the lumenal side of the endoplasmic reticulum. Studies on mutated carboxypeptidase yscY species. FEBS Lett. 443, 241–245 (1999).

    CAS  PubMed  Google Scholar 

  67. Heinrich, S. U., Mothes, W., Brunner, J. & Rapoport, T. A. The Sec61p complex mediates the integration of a membrane protein by allowing lipid partitioning of the transmembrane domain. Cell 102, 233–244 (2000).

    CAS  PubMed  Google Scholar 

  68. Hiller, M. M., Finger, A., Schweiger, M. & Wolf, D. H. ER degradation of a misfolded luminal protein by the cytosolic ubiquitin–proteasome pathway. Science 273, 1725–1728 (1996).

    CAS  PubMed  Google Scholar 

  69. Biederer, T., Volkwein, C. & Sommer, T. Degradation of subunits of the Sec61p complex, an integral component of the ER membrane, by the ubiquitin–proteasome pathway. EMBO J. 15, 2069–2076 (1996).

    CAS  PubMed  PubMed Central  Google Scholar 

  70. Ward, C. L., Omura, S. & Kopito, R. R. Degradation of CFTR by the ubiquitin–proteasome pathway. Cell 83, 121–127 (1995).

    CAS  PubMed  Google Scholar 

  71. Yu, H. & Kopito, R. R. The role of multiubiquitination in dislocation and degradation of the α-subunit of the T cell antigen receptor. J. Biol. Chem. 274, 36852–36858 (1999).

    CAS  PubMed  Google Scholar 

  72. Kikkert, M. et al. Ubiquitination is essential for human cytomegalovirus US11-mediated dislocation of MHC class I molecules from the endoplasmic reticulum to the cytosol. Biochem. J. 358, 369–377 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  73. Shamu, C. E., Flierman, D., Ploegh, H. L., Rapoport, T. A. & Chau, V. Polyubiquitination is required for US11-dependent movement of MHC class I heavy chain from endoplasmic reticulum into cytosol. Mol. Biol. Cell 12, 2546–2555 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  74. Shamu, C. E., Story, C. M., Rapoport, T. A. & Ploegh, H. L. The pathway of US11-dependent degradation of MHC class I heavy chains involves a ubiquitin-conjugated intermediate. J. Cell Biol. 147, 45–58 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  75. Ye, Y., Meyer, H. H. & Rapoport, T. A. The AAA ATPase Cdc48/p97 and its partners transport proteins from the ER into the cytosol. Nature 414, 652–656 (2001).This paper, and references 91, 97– 99 , show that the AAA ATPase Cdc48/p97 and its partners Ufd1 and Npl4 are involved in ER-protein degradation. The complex seems to extract proteins from the ER membrane.

    CAS  PubMed  Google Scholar 

  76. Biederer, T., Volkwein, C. & Sommer, T. Role of Cue1p in ubiquitination and degradation at the ER surface. Science 278, 1806–1809 (1997).

    CAS  PubMed  Google Scholar 

  77. Sommer, T. & Jentsch, S. A protein translocation defect linked to ubiquitin conjugation at the endoplasmic reticulum. Nature 365, 176–179 (1993).This paper gives the first evidence for the involvement of ubiquitylation in ER-protein degradation. The absence of a ubiquitin-conjugating enzyme (Ubc6) suppresses a sec61 mutant, which indicates that a misfolded membrane protein is stabilized.

    CAS  PubMed  Google Scholar 

  78. Hampton, R. Y. & Bhakta, H. Ubiquitin-mediated regulation of 3-hydroxy-3-methylglutaryl-CoA reductase. Proc. Natl Acad. Sci. USA 94, 12944–12948 (1997).

    CAS  PubMed  PubMed Central  Google Scholar 

  79. Plemper, R. K., Egner, R., Kuchler, K. & Wolf, D. H. Endoplasmic reticulum degradation of a mutated ATP-binding cassette transporter Pdr5 proceeds in a concerted action of Sec61 and the proteasome. J. Biol. Chem. 273, 32848–32856 (1998).

    CAS  PubMed  Google Scholar 

  80. Hill, K. & Cooper, A. A. Degradation of unassembled Vph1p reveals novel aspects of the yeast ER quality control system. EMBO J. 19, 550–561 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  81. Hampton, R. Y., Gardner, R. G. & Rine, J. Role of 26S proteasome and HRD genes in the degradation of 3-hydroxy-3-methylglutaryl-CoA reductase, an integral endoplasmic reticulum membrane protein. Mol. Biol. Cell 7, 2029–2044 (1996).This paper and reference 82 describe genetic screens in yeast to identify components that are involved in ER protein degradation.

    CAS  PubMed  PubMed Central  Google Scholar 

  82. Knop, M., Finger, A., Braun, T., Hellmuth, K. & Wolf, D. H. Der1, a novel protein specifically required for endoplasmic reticulum degradation in yeast. EMBO J. 15, 753–763 (1996).

    CAS  PubMed  PubMed Central  Google Scholar 

  83. Bordallo, J., Plemper, R. K., Finger, A. & Wolf, D. H. Der3p/Hrd1p is required for endoplasmic reticulum-associated degradation of misfolded lumenal and integral membrane proteins. Mol. Biol. Cell 9, 209–222 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  84. Bays, N. W., Gardner, R. G., Seelig, L. P., Joazeiro, C. A. & Hampton, R. Y. Hrd1p/Der3p is a membrane-anchored ubiquitin ligase required for ER-associated degradation. Nature Cell Biol. 3, 24–29 (2001).This article shows that Hrd1/Der3 functions as a ubiquitin-ligase in ER-protein degradation.

    CAS  PubMed  Google Scholar 

  85. Deak, P. M. & Wolf, D. H. Membrane topology and function of Der3/Hrd1p as a ubiquitin-protein ligase (E3) involved in endoplasmic reticulum degradation. J. Biol. Chem. 276, 10663–10669 (2001).

    CAS  PubMed  Google Scholar 

  86. Plemper, R. K. et al. Genetic interactions of Hrd3p and Der3p/Hrd1p with Sec61p suggest a retro-translocation complex mediating protein transport for ER degradation. J. Cell Sci. 112, 4123–4134 (1999).

    CAS  PubMed  Google Scholar 

  87. Gardner, R. G. et al. Endoplasmic reticulum degradation requires lumen to cytosol signaling. Transmembrane control of Hrd1p by Hrd3p. J. Cell Biol. 151, 69–82 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  88. Fang, S. et al. The tumor autocrine motility factor receptor, gp78, is a ubiquitin protein ligase implicated in degradation from the endoplasmic reticulum. Proc. Natl Acad. Sci. USA 98, 14422–14427 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  89. Swanson, R., Locher, M. & Hochstrasser, M. A conserved ubiquitin ligase of the nuclear envelope/endoplasmic reticulum that functions in both ER-associated and Matα2 repressor degradation. Genes Dev. 15, 2660–2674 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  90. Breitschopf, K., Bengal, E., Ziv, T., Admon, A. & Ciechanover, A. A novel site for ubiquitination: the N-terminal residue, and not internal lysines of MyoD, is essential for conjugation and degradation of the protein. EMBO J. 17, 5964–5973 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  91. Jarosch, E. et al. Protein dislocation from the ER requires polyubiquitination and the AAA-ATPase Cdc48. Nature Cell Biol. 4, 134–139 (2002).

    CAS  PubMed  Google Scholar 

  92. Riezman, H. The ins and outs of protein translocation. Science 278, 1728–1729 (1997).

    CAS  PubMed  Google Scholar 

  93. Mayer, T. U., Braun, T. & Jentsch, S. Role of the proteasome in membrane extraction of a short-lived ER-transmembrane protein. EMBO J. 17, 3251–3257 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  94. Huppa, J. B. & Ploegh, H. L. The α chain of the T cell antigen receptor is degraded in the cytosol. Immunity 7, 113–122 (1997).

    CAS  PubMed  Google Scholar 

  95. Yang, M., Omura, S., Bonifacino, J. S. & Weissman, A. M. Novel aspects of degradation of T cell receptor subunits from the endoplasmic reticulum (ER) in T cells: importance of oligosaccharide processing, ubiquitination, and proteasome-dependent removal from ER membranes. J. Exp. Med. 187, 835–846 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  96. Hirsch, C. & Ploegh, H. L. Intracellular targeting of the proteasome. Trends Cell Biol. 10, 268–272 (2000).

    CAS  PubMed  Google Scholar 

  97. Bays, N. W., Wilhovsky, S. K., Goradia, A., Hodgkiss-Harlow, K. & Hampton, R. Y. HRD4/NPL4 is required for the proteasomal processing of ubiquitinated ER proteins. Mol. Biol. Cell 12, 4114–4128 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  98. Rabinovich, E., Kerem, A., Frohlich, K. U., Diamant, N. & Bar-Nun, S. AAA-ATPase p97/Cdc48p, a cytosolic chaperone required for endoplasmic reticulum-associated protein degradation. Mol. Cell. Biol. 22, 626–634 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  99. Braun, S., Matuschewski, K., Rape, M., Thoms, S. & Jentsch, S. Role of the ubiquitin-selective CDC48(UFD1/NPL4) chaperone (segregase) in ERAD of OLE1 and other substrates. EMBO J. 21, 615–621 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  100. Zhang, X. et al. Structure of the AAA ATPase p97. Mol. Cell 6, 1473–1484 (2000).

    CAS  PubMed  Google Scholar 

  101. Patel, S. & Latterich, M. The AAA team: related ATPases with diverse functions. Trends Cell Biol. 8, 65–71 (1998).

    CAS  PubMed  Google Scholar 

  102. Kondo, H. et al. p47 is a cofactor for p97-mediated membrane fusion. Nature 388, 75–78 (1997).

    CAS  PubMed  Google Scholar 

  103. Hitchcock, A. L. et al. The conserved npl4 protein complex mediates proteasome-dependent membrane-bound transcription factor activation. Mol. Biol. Cell 12, 3226–3241 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  104. Rape, M. et al. Mobilization of processed, membrane-tethered SPT23 transcription factor by CDC48(UFD1/NPL4), a ubiquitin-selective chaperone. Cell 107, 667–677 (2001).

    CAS  PubMed  Google Scholar 

  105. Meyer, H. H., Shorter, J. G., Seemann, J., Pappin, D. & Warren, G. A complex of mammalian ufd1 and npl4 links the AAA-ATPase, p97, to ubiquitin and nuclear transport pathways. EMBO J. 19, 2181–2192 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  106. Singleton, M. R., Sawaya, M. R., Ellenberger, T. & Wigley, D. B. Crystal structure of T7 gene 4 ring helicase indicates a mechanism for sequential hydrolysis of nucleotides. Cell 101, 589–600 (2000).

    CAS  PubMed  Google Scholar 

  107. Schmidt, M., Lupas, A. N. & Finley, D. Structure and mechanism of ATP-dependent proteases. Curr. Opin. Chem. Biol. 3, 584–591 (1999).

    CAS  PubMed  Google Scholar 

  108. Langer, T. AAA proteases: cellular machines for degrading membrane proteins. Trends Biochem. Sci. 25, 247–251 (2000).

    CAS  PubMed  Google Scholar 

  109. Dai, R. M. & Li, C. C. Valosin-containing protein is a multi-ubiquitin chain-targeting factor required in ubiquitin–proteasome degradation. Nature Cell Biol. 3, 740–744 (2001).

    CAS  PubMed  Google Scholar 

  110. Pollard, M. G., Travers, K. J. & Weissman, J. S. Ero1p: a novel and ubiquitous protein with an essential role in oxidative protein folding in the endoplasmic reticulum. Mol. Cell 1, 171–182 (1998).

    CAS  PubMed  Google Scholar 

  111. Frand, A. R. & Kaiser, C. A. The ERO1 gene of yeast is required for oxidation of protein dithiols in the endoplasmic reticulum. Mol. Cell 1, 161–170 (1998).

    CAS  PubMed  Google Scholar 

Download references

Acknowledgements

We thank T. Sommer, K. Matlack, H. Ploegh and D. Finley for critical reading of the manuscript and helpful comments. B.T. is a fellow of the Damon Runyon Cancer Research Foundation and Y.Y. is a Helen Hay Whitney Fellow. The work in the authors' laboratory was supported by the National Institute of Health. T.A.R. is a Howard Hughes Medical Institute Investigator.

Author information

Authors and Affiliations

  1. Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, 02115, MA, USA

    Billy Tsai, Yihong Ye & Tom A. Rapoport

Authors
  1. Billy Tsai
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yihong Ye
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Tom A. Rapoport
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Tom A. Rapoport.

Related links

Related links

DATABASES

Interpro

RING-H2 domain

LocusLink

PDI

<i>Saccharomyces</i> Genome Database

Cdc48

Cue1

Eps1

Ero1

Hrd1

Hrd3

Htm1

Jem1

Kar2

Npl4

Scj1

Sec61

Sec62

Sec63

Ubc1

Ubc6

Ubc7

Ufd1

Yme1

Yta10

Yta12

Swiss-Prot

Bst1

cystic fibrosis transmembrane regulator

E1 enzyme

EDEM

HMG CoA reductase

NSF

p97

UGGT

US2

US11

Glossary

CHAPERONES

A class of proteins that bind unfolded or partially folded polypeptides, prevent their aggregation and promote their folding.

LYSOSOME

An organelle (called the vacuole in yeast) that contains many hydrolytic enzymes. Lysosomes degrade proteins that are imported into the cell by endocytosis, which are diverted to them from the secretory pathway, or taken up from the cytosol by autophagy.

INCLUSION BODIES

Protein precipitates that are formed in the cytosol, often after protein overexpression.

CARBOXYPEPTIDASE Y

Carboxypeptidase Y (CPY) is a protease that is transported from the endoplasmic reticulum (ER) to the vacuole of Saccharomyces cerevisiae cells. A misfolded version, CPY*, is retained in the ER, retro-translocated into the cytosol and degraded by the proteasome.

MICROSOMES

A membrane fraction that consists largely of ER, and sediments slowly in the centrifuge.

PRO-α-FACTOR

Pro-α-factor is the precursor of α-factor, a peptide secreted by S. cerevisiae cells for mating. In the ER lumen, pro-α-factor is generated by signal-sequence cleavage from prepro-α-factor and is glycosylated. When unglycosylated, it is misfolded, retro-translocated and degraded in the cytosol.

[H+]ATPase

A plasma membrane protein, which uses the energy of ATP to pump protons out of the cell.

APOLIPOPROTEIN

Lipoprotein particles have a monolayer of phospholipids at their surface, into which apolipoproteins are embedded. The latter are translocated across the ER membrane in liver cells and associate with cholesterol esters as they emerge on the lumenal side of the ER.

β2-MICROGLOBULIN

A soluble, lumenal ER protein, which associates with the heavy chain of the major histocompatibility class I complex.

AAA FAMILY OF ATPases

ATPases, which are associated with diverse cellular activities, contain a conserved domain of 200–250 amino acids. This domain includes Walker A and B motifs, which are required for ATP binding and hydrolysis.

SNARE COMPLEXES

(SNARE, soluble N-ethylmaleimide sensitive factor attachment protein receptor). A vesicle-bound v-SNARE polypeptide associates with the three chains of a t-SNARE in the target membrane to form a stable complex, which might drive fusion of the two membranes.

ClpP

A bacterial protease, which, like the eukaryotic proteasome, forms a cylinder with active sites in the interior. A ring of ATPases that is formed by ClpA feed polypeptides into ClpP.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Tsai, B., Ye, Y. & Rapoport, T. Retro-translocation of proteins from the endoplasmic reticulum into the cytosol. Nat Rev Mol Cell Biol 3, 246–255 (2002). https://doi.org/10.1038/nrm780

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1038/nrm780

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing