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:

Shaping the composition of the mitochondrial outer membrane

Nature Cell Biology volume 27, pages 890–901 (2025)Cite this article

Subjects

Abstract

Mitochondria are critical double-membraned organelles that act as biosynthetic and bioenergetic cellular factories, with the outer membrane providing an interface with the rest of the cell. Mitochondrial outer membrane proteins regulate a variety of processes, including metabolism, innate immunity and apoptosis. Although the biophysical and functional diversity of these proteins is highly documented, the mechanisms of their biogenesis and the integration of that into cellular homeostasis are just starting to take shape. Here, focusing on α-helical outer membrane proteins, we review recent insights into the mechanisms of synthesis and cytosolic chaperoning, insertion and assembly in the lipid bilayer, and quality control of unassembled or mislocalized transmembrane domains. We further discuss the role convergent evolution played in this process, comparing key biogenesis players from lower eukaryotes, including yeast and trypanosomes, with multicellular metazoan systems, and draw comparisons with the endoplasmic reticulum biogenesis system, in which membrane proteins face similar challenges.

Access through your institution
Buy or subscribe

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

Access options

Access through your institution

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

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

Fig. 1: Cytosolic targeting of mitochondrial proteins.
Fig. 2: OMM protein insertion.
Fig. 3: Membrane insertases potentially act as lipid scramblases.
Fig. 4: Quality control of OMM α-helical proteins.
Fig. 5: Schematic comparing α-helical protein biogenesis at the ER and OMM.

Similar content being viewed by others

References

  1. Von Heijne, G. The membrane protein universe: what’s out there and why bother? J. Intern. Med. 261, 543–557 (2007).

    Article  Google Scholar 

  2. Hegde, R. S. & Keenan, R. J. The mechanisms of integral membrane protein biogenesis. Nat. Rev. Mol. Cell Biol. 23, 107–124 (2022).

    Article  CAS  PubMed  Google Scholar 

  3. Rapoport, T. A., Li, L. & Park, E. Structural and mechanistic insights into protein translocation. Annu. Rev. Cell Dev. Biol. 33, 369–390 (2017).

    Article  CAS  PubMed  Google Scholar 

  4. Wickner, W. & Schekman, R. Protein translocation across biological membranes. Science 310, 1452–1456 (2005).

    Article  CAS  PubMed  Google Scholar 

  5. Rapoport, T. A. Protein translocation across the eukaryotic endoplasmic reticulum and bacterial plasma membranes. Nature 450, 663–669 (2007).

    Article  CAS  PubMed  Google Scholar 

  6. White, S. H. & von Heijne, G. How translocons select transmembrane helices. Annu. Rev. Biophys. 37, 23–42 (2008).

    Article  CAS  PubMed  Google Scholar 

  7. Friedman, J. R. & Nunnari, J. Mitochondrial form and function. Nature 505, 335–343 (2014).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Guna, A. & Hegde, R. S. Transmembrane domain recognition during membrane protein biogenesis and quality control. Curr. Biol. 28, R498–R511 (2018).

    Article  CAS  PubMed  Google Scholar 

  9. Becker, T., Song, J. & Pfanner, N. Versatility of preprotein transfer from the cytosol to mitochondria. Trends Cell. Biol. 7, 534–548 (2019).

    Article  Google Scholar 

  10. Gupta, A. & Becker, T. Mechanisms and pathways of mitochondrial outer membrane protein biogenesis. Biochem. Biophys. Acta Bioenerg. 1862, 148323 (2021).

    Article  CAS  Google Scholar 

  11. Wiedemann, N. et al. Machinery for protein sorting and assembly in the mitochondrial outer membrane. Nature 424, 565–571 (2003).

    Article  CAS  PubMed  Google Scholar 

  12. Paschen, S. A. et al. Evolutionary conservation of biogenesis of β-barrel membrane proteins. Nature 426, 862–866 (2003).

    Article  CAS  PubMed  Google Scholar 

  13. Höhr, A. I. C. et al. Membrane protein insertion through a mitochondrial β-barrel gate. Science 359, eaah6834 (2018).

    Article  PubMed  PubMed Central  Google Scholar 

  14. Diederichs, K. A. et al. Structural insight into mitochondrial β-barrel outer membrane protein biogenesis. Nat. Commun. 11, 3290 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  15. Muthukumar, G. et al. Triaging of α-helical proteins to the mitochondrial outer membrane by distinct chaperone machinery based on substrate topology. Mol. Cell 84, 1101–1119.e9 (2024).

    Article  CAS  PubMed  Google Scholar 

  16. Drwesh, L. et al. A network of cytosolic (co)chaperones promotes the biogenesis of mitochondrial signal-anchored outer membrane proteins. eLife 11, e77706 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  17. Doan, K. N. et al. The mitochondrial import complex MIM functions as main translocase for a-helical outer membrane proteins. Cell Rep. 31, 107567 (2020).

    Article  CAS  PubMed  Google Scholar 

  18. Vitali, D. G. et al. Independent evolution of functionally exchangeable mitochondrial outer membrane import complexes. eLife 7, e34488 (2018).

    Article  PubMed  PubMed Central  Google Scholar 

  19. Guna, A. et al. MTCH2 is a mitochondrial outer membrane protein insertase. Science 378, 317–322 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  20. Bykov, Y. S., Rapaport, D., Herrmann, J. M. & Schuldiner, M. Cytosolic events in the biogenesis of mitochondrial proteins. Trends Biochem. Sci. 45, 650–667 (2020).

    Article  CAS  PubMed  Google Scholar 

  21. Kellems, R. E., Allison, V. F. & Butow, R. A. Cytoplasmic type 80 S ribosomes associated with yeast mitochondria. II. Evidence for the association of cytoplasmic ribosomes with the outer mitochondrial membrane in situ. J. Biol. Chem. 249, 3297–3303 (1974).

    Article  CAS  PubMed  Google Scholar 

  22. Kellems, R. E., Allison, V. F. & Butow, R. A. Cytoplasmic type 80S ribosomes associated with yeast mitochondria. IV. Attachment of ribosomes to the outer membrane of isolated mitochondria. J. Cell Biol. 65, 1–14 (1975).

    Article  CAS  PubMed  Google Scholar 

  23. Gold, V. A., Chroscicki, P., Bragoszewski, P. & Chacinska, A. Visualization of cytosolic ribosomes on the surface of mitochondria by electron cryo-tomography. EMBO Rep. 18, 1786–1800 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  24. Fazal, F. M. et al. Atlas of subcellular RNA localization revealed by APEX-seq. Cell 178, 473–490 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Williams, C. C., Jan, C. H. & Weissman, J. S. Targeting and plasticity of mitochondrial proteins revealed by proximity-specific ribosome profiling. Science 346, 748–751 (2014).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Deshaies, R. J., Koch, B. D., Werner-Washburne, M., Craig, E. A. & Schekman, R. A subfamily of stress proteins facilitates translocation of secretory and mitochondrial precursor polypeptides. Nature 332, 800–805 (1988).

    Article  CAS  PubMed  Google Scholar 

  27. Young, J. C., Hoogenraad, N. J. & Hartl, F. U. Molecular chaperones Hsp90 and Hsp70 deliver preproteins to the mitochondrial import receptor Tom70. Cell 112, 41–50 (2003).

    Article  CAS  PubMed  Google Scholar 

  28. Fan, A. C. Y., Bhangoo, M. K. & Young, J. C. Hsp90 functions in the targeting and outer membrane translocation steps of Tom70-mediated mitochondrial import. J. Biol. Chem. 28, 33313–33324 (2006).

    Article  Google Scholar 

  29. Bloss, T. A., Witze, E. S. & Rothman, J. H. Suppression of CED-3-independent apoptosis by mitochondrial βNAC in Caenorhabditis elegans. Nature 424, 1066–1071 (2003).

    Article  CAS  PubMed  Google Scholar 

  30. Markesich, D. C., Gajewski, K. M., Nazimiec, M. E. & Beckingham, K. bicaudal encodes the Drosophila beta NAC homolog, a component of the ribosomal translational machinery. Development 127, 559–572 (2000).

    Article  CAS  PubMed  Google Scholar 

  31. Fünfschilling, U. & Rospert, S. Nascent polypeptide-associated complex stimulates protein import into yeast mitochondria. Mol. Biol. Cell. 10, 3289–3299 (1999).

    Article  PubMed  PubMed Central  Google Scholar 

  32. Lesnik, C., Cohen, Y., Atir-Lande, A., Schuldiner, M. & Arava, Y. OM14 is a mitochondrial receptor for cytosolic ribosomes that supports co-translational import into mitochondria. Nat. Commun. 5, 5711 (2014).

    Article  CAS  PubMed  Google Scholar 

  33. Ponce-Rojas, J. C. et al. αβ’-NAC cooperates with Sam37 to mediate early stages of mitochondrial protein import. FEBS J. 284, 814–830 (2017).

    Article  CAS  PubMed  Google Scholar 

  34. Lauring, B., Sakai, H., Kreibich, G. & Wiedmann, M. Nascent polypeptide-associated complex protein prevents mistargeting of nascent chains to the endoplasmic reticulum. Proc. Natl Acad. Sci. USA 92, 5411–5415 (1995).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  35. Gamerdinger, M., Hanebuth, M. A., Frickey, T. & Deuerling, E. The principle of antagonism ensures protein targeting specificity at the endoplasmic reticulum. Science 348, 201–207 (2015).

    Article  CAS  PubMed  Google Scholar 

  36. Jomaa, A. et al. Mechanism of signal sequence handover from NAC to SRP on ribosomes during ER-protein targeting. Science 375, 839–844 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  37. Sheffield, W. P., Shore, G. C. & Randall, S. K. Mitochondrial precursor protein. Effects of 70-kilodalton heat shock protein on polypeptide folding, aggregation, and import competence. J. Biol. Chem. 265, 11069–11076 (1990).

    Article  CAS  PubMed  Google Scholar 

  38. Jores, T. et al. Cytosolic Hsp70 and Hsp40 chaperones enable the biogenesis of mitochondrial β-barrel proteins. J. Cell Biol. 217, 30913108 (2018).

    Article  Google Scholar 

  39. Hoseini, H. et al. The cytosolic cochaperone Sti1 is relevant for mitochondrial biogenesis and morphology. FEBS J. 283, 3338–3352 (2016).

    Article  CAS  PubMed  Google Scholar 

  40. Zara, V., Ferramosca, A., Robitaille-Foucher, P., Palmieri, F. & Young, J. C. Mitochondrial carrier protein biogenesis: role of the chaperones Hsc70 and Hsp90. Biochem. J. 419, 369–375 (2009).

    Article  CAS  PubMed  Google Scholar 

  41. Bhangoo, M. K. et al. Multiple 40-kDa heat-shock protein chaperones function in Tom70-dependent mitochondrial import. Mol. Biol. Cell. 18, 3414–3428 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  42. Artigues, A., Iriarte, A. & Martinez-Carrion, M. Binding to chaperones allows import of a purified mitochondrial precursor into mitochondria. J. Biol. Chem. 277, 25047–25055 (2002).

    Article  CAS  PubMed  Google Scholar 

  43. Caplan, A. J., Cyr, D. M. & Douglas, M. G. YDJ1p facilitates polypeptide translocation across different intracellular membranes by a conserved mechanism. Cell 71, 1143–1155 (1992).

    Article  CAS  PubMed  Google Scholar 

  44. Kanazawa, M., Terada, K., Kato, S. & Mori, M. HSDJ, a human homolog of DnaJ, is farnesylated and is involved in protein import into mitochondria. J. Biochem. 121, 890–895 (1997).

    Article  CAS  PubMed  Google Scholar 

  45. Kampinga, H. H. & Craig, E. A. The HSP70 chaperone machinery: J proteins as drivers of functional specificity. Nat. Rev. Mol. Cell Biol. 11, 579–592 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  46. Przybyla, L. & Gilbert, L. A. A new era in functional genomics screens. Nat. Rev. Genet. 23, 89–103 (2022).

    Article  CAS  PubMed  Google Scholar 

  47. Bock, C. et al. High-content CRISPR screening. Nat. Rev. Methods Prim. 2, 8 (2022).

    Article  CAS  Google Scholar 

  48. Lotz, G. P., Brychzy, A., Heinz, S. & Obermann, W. M. A novel HSP90 chaperone complex regulates intracellular vesicle transport. J. Cell Sci. 121, 717–723 (2008).

    Article  CAS  PubMed  Google Scholar 

  49. Philp, L. K. et al. SGTA: a new player in the molecular co-chaperone game. Horm. Cancer 4, 343–357 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  50. Cho, H. & Shan, S. O. Substrate relay in an Hsp70-cochaperone cascade safeguards tail-anchored membrane protein targeting. EMBO J. 37, e99264 (2018).

    Article  PubMed  PubMed Central  Google Scholar 

  51. Abe, Y. et al. Structural basis of presequence recognition by the mitochondrial protein import receptor Tom20. Cell 100, 551–560 (2000).

    Article  CAS  PubMed  Google Scholar 

  52. Su, J. et al. Structural basis of Tom20 and Tom22 cytosolic domains as the human TOM complex receptors. Proc. Natl Acad. Sci. USA 119, e2200158119 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  53. Hill, K. et al. Tom40 forms the hydrophilic channel of the mitochondrial import pore for preproteins. Nature 395, 516–521 (1998).

    Article  CAS  PubMed  Google Scholar 

  54. Tucker, K. & Park, E. Cryo-EM structure of the mitochondrial protein-import channel TOM complex at near-atomic resolution. Nat. Struct. Mol. Biol. 12, 1158–1166 (2019).

    Article  Google Scholar 

  55. Wiedemann, N. & Pfanner, N. Mitochondrial machineries for protein import and assembly. Annu. Rev. Biochem. 86, 685–714 (2017).

    Article  CAS  PubMed  Google Scholar 

  56. Kutik, S. et al. Dissecting membrane insertion of mitochondrial β-barrel proteins. Cell 132, 1011–1024 (2008).

    Article  CAS  PubMed  Google Scholar 

  57. Walther, D. M. & Rapaport, D. Biogenesis of mitochondrial outer membrane proteins. Biochem. Biophys. Acta 1793, 42–51 (2009).

    Article  CAS  PubMed  Google Scholar 

  58. Becker, T. et al. The mitochondrial import protein Mim1 promotes biogenesis of multispanning outer membrane proteins. J. Cell Biol. 194, 387–395 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  59. Krüger, V. et al. Identification of new channels by systematic analysis of the mitochondrial outer membrane. J. Cell Biol. 216, 3485–3495 (2017).

    Article  PubMed  PubMed Central  Google Scholar 

  60. Käser, S. et al. Outer membrane protein functions as integrator of protein import and DNA inheritance in mitochondria. Proc. Natl Acad. Sci. USA 113, E4467–E4475 (2016).

    Article  PubMed  PubMed Central  Google Scholar 

  61. Dimmer, K. S. et al. A crucial role for Mim2 in the biogenesis of mitochondrial outer membrane proteins. J. Cell Sci. 125, 3464–3473 (2012).

    CAS  PubMed  Google Scholar 

  62. Lueder, F. & Lithgow, T. The three domains of the mitochondrial outer membrane protein Mim1 have discrete functions in assembly of the TOM complex. FEBS Lett. 583, 1475–1480 (2009).

    Article  CAS  PubMed  Google Scholar 

  63. Busch, J. D., Fielden, L. F., Pfanner, N. & Wiedemann, N. Mitochondrial protein transport: versatility of translocases and mechanisms. Mol. Cell 83, 890–910 (2023).

    Article  CAS  PubMed  Google Scholar 

  64. Ruprecht, J. J. & Kunji, E. R. S. The SLC25 mitochondrial carrier family: structure and mechanism. Trends Biochem. Sci. 45, 244–258 (2020).

    Article  CAS  PubMed  Google Scholar 

  65. Pleiner, T. et al. Structural basis for membrane insertion by the human ER membrane protein complex. Science 369, 433–436 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  66. Wu, X. et al. Structural basis of ER-associated protein degradation mediated by the Hrd1 ubiquitin ligase complex. Science 368, eaaz2449 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  67. Kumazaki, K. et al. Structural basis of Sec-independent membrane protein insertion by YidC. Nature 509, 516–520 (2014).

    Article  CAS  PubMed  Google Scholar 

  68. Dimogkioka, A. R., Elias, A. & Rapaport, D. The mammalian protein MTCH1 can function as an insertase. Preprint at bioRxiv https://doi.org/10.1101/2024.12.11.627916 (2024).

  69. Labbé, K. et al. The modified mitochondrial outer membrane carrier MTCH2 links mitochondrial fusion to lipogenesis. J. Cell Biol. 220, e202103122 (2021).

    Article  PubMed  PubMed Central  Google Scholar 

  70. Rottiers, V. et al. MTCH2 is a conserved regulator of lipid homeostasis. Obesity 25, 616–625 (2017).

    Article  CAS  PubMed  Google Scholar 

  71. Chitwood, P. J. & Hegde, R. S. An intramembrane chaperone complex facilitates membrane protein biogenesis. Nature 584, 630–634 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  72. Brix, J., Dietmeier, K. & Pfanner, N. Differential recognition of preproteins by the purified cytosolic domains of the mitochondrial import receptors Tom20, Tom22, and Tom70. J. Biol. Chem. 272, 20730–20735 (1997).

    Article  CAS  PubMed  Google Scholar 

  73. Van Wilpe, S. et al. Tom22 is a multifunctional organizer of the mitochondrial preprotein translocase. Nature 401, 485–489 (1999).

    Article  PubMed  Google Scholar 

  74. Yamano, K. et al. Tom20 and Tom22 share the common signal recognition pathway in mitochondrial protein import. J. Biol. Chem. 283, 3799–3807 (2008).

    Article  CAS  PubMed  Google Scholar 

  75. Brix, J. et al. The mitochondrial import receptor Tom70: identification of a 25 kDa core domain with a specific binding site for preproteins. J. Mol. Biol. 303, 479–488 (2000).

    Article  CAS  PubMed  Google Scholar 

  76. Backes, S. et al. Tom70 enhances mitochondrial preprotein import efficiency by binding to internal targeting sequences. J. Cell Biol. 217, 1369–1382 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  77. Backes, S. et al. The chaperone-binding activity of the mitochondrial surface receptor Tom70 protects the cytosol against mitoprotein-induced stress. Cell Rep. 35, 108936 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  78. Kato, H., Lu, Q., Rapaport, D. & Kozjak-Pavlovic, V. Tom70 is essential for PINK1 import into mitochondria. PLoS ONE 8, e58435 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  79. Vance, D. E., Choy, P. C., Farren, S. B., Lim, P. H. & Schneider, W. J. Asymmetry of phospholipid biosynthesis. Nature 270, 268–269 (1977).

    Article  CAS  PubMed  Google Scholar 

  80. Vance, J. E. Phospholipid synthesis and transport in mammalian cells. Traffic 16, 1–18 (2015).

    Article  CAS  PubMed  Google Scholar 

  81. Reinisch, K. M. & Prinz, W. A. Mechanisms of nonvesicular lipid transport. J. Cell Biol. 220, e202012058 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  82. Pomorski, T. & Menon, A. K. Lipid flippases and their biological functions. Cell. Mol. Life Sci. 63, 2908–2921 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  83. Bethel, N. P. & Grabe, M. Atomistic insight into lipid translocation by a TMEM16 scramblase. Proc. Natl Acad. Sci. USA 113, 14049–14054 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  84. Li, D., Rocha-Roa, C., Schilling, M. A., Reinisch, K. M. & Vanni, S. Lipid scrambling is a general feature of protein insertases. Proc. Natl Acad. Sci. USA 121, e2319476121 (2024).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  85. Itakura, E. et al. Ubiquilins chaperone and triage mitochondrial membrane proteins for degradation. Mol. Cell 63, 21–33 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  86. Deng, H. X. et al. Mutations in UBQLN2 cause dominant X-linked juvenile and adult-onset ALS and ALS/dementia. Nature 477, 211–215 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  87. Rodrigo-Brenni, M. C., Gutierrez, E. & Hegde, R. S. Cytosolic quality control of mislocalized proteins requires RNF126 recruitment to Bag6. Mol. Cell 55, 227–237 (2014).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  88. Shao, S., Rodrigo-Brenni, M. C., Kivlen, M. H. & Hegde, R. S. Mechanistic basis for a molecular triage reaction. Science 355, 298–302 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  89. Wohlever, M. L., Mateja, A., McGilvray, P. T., Day, K. J. & Keenan, R. J. Msp1 Is a membrane protein dislocase for tail-anchored proteins. Mol. Cell 67, 194–202.e6 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  90. Matsumoto, S. et al. Msp1 clears mistargeted proteins by facilitating their transfer from mitochondria to the ER. Mol. Cell 76, 191–205.e10 (2019).

    Article  CAS  PubMed  Google Scholar 

  91. Wang, L., Toutkoushian, H., Belyy, V., Kokontis, C. Y. & Walter, P. Conserved structural elements specialize ATAD1 as a membrane protein extraction machine. eLife 11, e73941 (2022).

    Article  PubMed  PubMed Central  Google Scholar 

  92. Kim, J. et al. ATAD1 prevents clogging of TOM and damage caused by un-imported mitochondrial proteins. Cell Rep. 43, 114473 (2024).

    Article  CAS  PubMed  Google Scholar 

  93. Wang, L. & Walter, P. Msp1/ATAD1 in protein quality control and regulation of synaptic activities. Annu. Rev. Cell Dev. Biol. 36, 141–164 (2020).

    Article  PubMed  Google Scholar 

  94. Weir, N. R., Kamber, R. A., Martenson, J. S. & Denic, V. The AAA protein Msp1 mediates clearance of excess tail-anchored proteins from the peroxisomal membrane. eLife 6, e28507 (2017).

    Article  PubMed  PubMed Central  Google Scholar 

  95. Cichocki, B. A., Krumpe, K., Vitali, D. G. & Rapaport, D. Pex19 is involved in importing dually targeted tail-anchored proteins to both mitochondria and peroxisomes. Traffic 19, 770–785 (2018).

    Article  CAS  PubMed  Google Scholar 

  96. Aravindan, N. et al. Mpf1 is a novel factor that affects the dual distribution of tail-anchored proteins between mitochondria and peroxisomes. EMBO Rep. https://doi.org/10.1038/s44319-025-00440-6 (2025).

  97. Nagashima, S., Tokuyama, T., Yonashiro, R., Inatome, R. & Yanagi, S. Roles of mitochondrial ubiquitin ligase MITOL/MARCH5 in mitochondrial dynamics and diseases. J. Biochem. 155, 273–279 (2014).

    Article  CAS  PubMed  Google Scholar 

  98. McKenna, M. J. et al. The endoplasmic reticulum P5A-ATPase is a transmembrane helix dislocase. Science 369, eabc5809 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  99. McKenna, M. J., Adams, B. M., Chu, V., Paulo, J. A. & Shao, S. ATP13A1 prevents ERAD of folding-competent mislocalized and misoriented proteins. Mol. Cell 82, 4277–4289 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  100. Mun, S. H. et al. Marchf6 E3 ubiquitin ligase critically regulates endoplasmic reticulum stress, ferroptosis, and metabolic homeostasis in POMC neurons. Cell Rep. 42, 112746 (2023).

    Article  CAS  PubMed  Google Scholar 

  101. Kikkert, M. et al. Human HRD1 is an E3 ubiquitin ligase involved in degradation of proteins from the endoplasmic reticulum. J. Biol. Chem. 279, 3525–3534 (2004).

    Article  CAS  PubMed  Google Scholar 

  102. Shao, S. & Hegde, R. S. Target selection during protein quality control. Trends Biochem. Sci. 41, 124–137 (2016).

    Article  CAS  PubMed  Google Scholar 

  103. Wang, S., Yang, C. I. & Shan, S. O. SecA mediates cotranslational targeting and translocation of an inner membrane protein. J. Cell Biol. 216, 3639–3653 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  104. Perry, A. J., Hulett, J. M., Likić, V. A., Lithgow, T. & Gooley, P. R. Convergent evolution of receptors for protein import into mitochondria. Curr. Biol. 16, 221–229 (2006).

    Article  CAS  PubMed  Google Scholar 

  105. Mani, J., Meisinger, C. & Schneider, A. Peeping at TOMs—diverse entry gates to mitochondria provide insights into the evolution of eukaryotes. Mol. Biol. Evol. 33, 337–351 (2016).

    Article  CAS  PubMed  Google Scholar 

  106. He, D. et al. An alternative root for the eukaryote tree of life. Curr. Biol. 24, 465–470 (2014).

    Article  CAS  PubMed  Google Scholar 

  107. Tsaousis, A. D. et al. A functional Tom70 in the human parasite Blastocystis sp.: implications for the evolution of the mitochondrial import apparatus. Mol. Biol. Evol. 28, 781–791 (2011).

    Article  CAS  PubMed  Google Scholar 

  108. Carrie, C., Murcha, M. W. & Whelan, J. An in silico analysis of the mitochondrial protein import apparatus of plants. BMC Plant Biol. 10, 249 (2010).

    Article  PubMed  PubMed Central  Google Scholar 

  109. Cavalier-Smith, T. Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree. Biol. Lett. 6, 342–345 (2010).

    Article  PubMed  Google Scholar 

  110. Gray, M. W., Burger, G. & Lang, B. F. Mitochondrial evolution. Science 283, 1476–1481 (1999).

    Article  CAS  PubMed  Google Scholar 

  111. Timmis, J. N., Ayliffe, M. A., Huang, C. Y. & Martin, W. Endosymbiotic gene transfer: organelle genomes forge eukaryotic chromosomes. Nat. Rev. Genet. 5, 123–135 (2004).

    Article  CAS  PubMed  Google Scholar 

  112. Rath, S. et al. MitoCarta3.0: an updated mitochondrial proteome now with sub-organelle localization and pathway annotations. Nucleic Acids Res. 49, D1541–D1547 (2021).

    Article  CAS  PubMed  Google Scholar 

  113. Chuang, K. H., Liang, F., Higgins, R. & Wang, Y. Ubiquilin/Dsk2 promotes inclusion body formation and vacuole (lysosome)-mediated disposal of mutated huntingtin. Mol. Biol. Cell. 27, 2025–2036 (2016).

    Article  PubMed  PubMed Central  Google Scholar 

  114. Chandel, N. S. Evolution of mitochondria as signaling organelles. Cell Metab. 22, 204–206 (2015).

    Article  CAS  PubMed  Google Scholar 

  115. Sun, Q. et al. The specific and essential role of MAVS in antiviral innate immune responses. Immunity 24, 633–642 (2006).

    Article  CAS  PubMed  Google Scholar 

  116. Vazquez, C. & Horner, S. M. MAVS coordination of antiviral innate immunity. J. Virol. 89, 6974–6977 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  117. Meng, E. C. et al. UCSF ChimeraX: tools for structure building and analysis. Protein Sci. 32, e4792 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  118. Hallgren, J. et al. DeepTMHMM predicts alpha and beta transmembrane proteins using deep neural networks. Preprint at bioRxiv https://doi.org/10.1101/2022.04.08.487609 (2022).

  119. Keenan, R. J., Freymann, D. M., Stroud, R. M. & Walter, P. The signal recognition particle. Annu. Rev. Biochem. 70, 755–775 (2001).

    Article  CAS  PubMed  Google Scholar 

  120. Voorhees, R. M. & Hegde, R. S. Structures of the scanning and engaged states of the mammalian SRP–ribosome complex. eLife 4, e07975 (2015).

    Article  PubMed  PubMed Central  Google Scholar 

  121. Mateja, A. et al. The structural basis of tail-anchored membrane protein recognition by Get3. Nature 461, 361–366 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  122. Voorhees, R. M., Fernández, I. S., Scheres, S. H. & Hegde, R. S. Structure of the mammalian ribosome–Sec61 complex to 3.4 Å resolution. Cell 157, 1632–1643 (2014).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  123. Schuldiner, M. et al. The GET complex mediates insertion of tail-anchored proteins into the ER membrane. Cell 134, 634–645 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  124. Miller-Vedam, L. E. et al. Structural and mechanistic basis of the EMC-dependent biogenesis of distinct transmembrane clients. eLife 9, e62611 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  125. McGilvray, P. T. et al. An ER translocon for multi-pass membrane protein biogenesis. eLife 9, e56889 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  126. Sundaram, A. et al. Substrate-driven assembly of a translocon for multipass membrane proteins. Nature 611, 167–172 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

Download references

Acknowledgements

This work was supported by US National Institutes of Health pre-doctoral training grant T32GM007287 (to G.M.) and the Howard Hughes Medical Institute (to J.S.W.). We also thank A. Guna, K. E. Yost and J. Nunnari for careful reading of and input on the manuscript.

Author information

Authors and Affiliations

  1. Whitehead Institute for Biomedical Research, Cambridge, MA, USA

    Gayathri Muthukumar & Jonathan S. Weissman

  2. Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA

    Gayathri Muthukumar & Jonathan S. Weissman

  3. Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA

    Jonathan S. Weissman

  4. David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA

    Jonathan S. Weissman

Authors
  1. Gayathri Muthukumar
    View author publications

    Search author on:PubMed Google Scholar

  2. Jonathan S. Weissman
    View author publications

    Search author on:PubMed Google Scholar

Contributions

G.M. and J.S.W. wrote the manuscript. G.M. designed the figures with the support of J.S.W.

Corresponding author

Correspondence to Jonathan S. Weissman.

Ethics declarations

Competing interests

J.S.W. declares outside interest in 5AM Venture, Amgen, nChroma Bio, DEM BioPharma, KSQ Therapeutics, Maze Therapeutics, Tenaya Therapeutics, Tessera Therapeutics, Thermo Fisher Scientific and Third Rock Ventures. G.M. declares no competing interests.

Peer review

Peer review information

Nature Cell Biology thanks Agnieszka Chacinska, Nikolaus Pfanner and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Muthukumar, G., Weissman, J.S. Shaping the composition of the mitochondrial outer membrane. Nat Cell Biol 27, 890–901 (2025). https://doi.org/10.1038/s41556-025-01683-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue date:

  • DOI: https://doi.org/10.1038/s41556-025-01683-0

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