A new mitofusin topology places the redox-regulated C terminus in the mitochondrial intermembrane space
Bibliographic record
Abstract
Mitochondrial fusion occurs in many eukaryotes, including animals, plants, and fungi. It is essential for cellular homeostasis, and yet the underlying mechanisms remain elusive. Comparative analyses and phylogenetic reconstructions revealed that fungal Fzo1 and animal Mitofusin proteins are highly diverged from one another and lack strong sequence similarity. Bioinformatic analysis showed that fungal Fzo1 proteins exhibit two predicted transmembrane domains, whereas metazoan Mitofusins contain only a single transmembrane domain. This prediction contradicts the current models, suggesting that both animal and fungal proteins share one topology. This newly predicted topology of Mfn1 and Mfn2 was demonstrated biochemically, confirming that the C-terminal, redox-sensitive cysteine residues reside within the intermembrane space (IMS). Functional experiments established that redox-mediated disulfide modifications within the IMS domain are key modulators of reversible Mfn oligomerization that drives fusion. Together, these results lead to a revised understanding of Mfns as single-spanning outer membrane proteins with an Nout–Cin orientation, providing functional insight into the IMS contribution to redox-regulated fusion events.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".