Selective quality control of mistargeted mitochondrial proteins at the endoplasmic reticulum

Verdict. Here, we show that mitochondrial import stress drives widespread rerouting of mitochondrial proteins to the endoplasmic reticulum (ER), with strong enrichment for hydrophobic oxidative phosphorylation (OXPHOS) components. It intersects mitochondrial stress/dysfunction themes (mitochondrial dysfunction; OXPHOS / ETC).

What the authors report

In eukaryotic cells, the function of each organelle depends on its unique protein composition. Protein targeting errors threaten organelle identity and function, yet how mistargeting errors are detected and resolved remains poorly understood.

Key results stated in the abstract include the following. Here, we show that mitochondrial import stress drives widespread rerouting of mitochondrial proteins to the endoplasmic reticulum (ER), with strong enrichment for hydrophobic oxidative phosphorylation (OXPHOS) components. Using proximity proteomics, a split-fluorescence reporter system, and genome-wide CRISPR screening, we find that mistargeted proteins partition into distinct classes with divergent fates, ranging from stable ER residence to rapid degradation by ER-associated degradation (ERAD). Together, these findings establish the ER as a key organelle for handling mistargeted mitochondrial proteins and reveal how ER quality control maintains proteostasis during mitochondrial dysfunction.

Why it matters for mitochondrial biology

Within mitochondrial research, this work maps primarily to OXPHOS, genetics. It is relevant to mitochondrial dysfunction discourse because the abstract invokes mitochondrial dysfunction, OXPHOS / ETC. That does not by itself establish a validated disease mechanism; it indicates thematic proximity. OXPHOS/ETC involvement, if confirmed, would place the work in the core of bioenergetic pathophysiology rather than peripheral organelle biology. Server: biorxiv. Posted 2026-08-17. Synthesis confidence is bounded by abstract completeness.

Study design (abstract-level)

Using proximity proteomics, a split-fluorescence reporter system, and genome-wide CRISPR screening, we find that mistargeted proteins partition into distinct classes with divergent fates, ranging from stable ER residence to rapid degradation by ER-associated degradation (ERAD).

Principal findings

1. Here, we show that mitochondrial import stress drives widespread rerouting of mitochondrial proteins to the endoplasmic reticulum (ER), with strong enrichment for hydrophobic oxidative phosphorylation (OXPHOS) components.
2. Using proximity proteomics, a split-fluorescence reporter system, and genome-wide CRISPR screening, we find that mistargeted proteins partition into distinct classes with divergent fates, ranging from stable ER residence to rapid degradation by ER-associated degradation (ERAD).
3. Together, these findings establish the ER as a key organelle for handling mistargeted mitochondrial proteins and reveal how ER quality control maintains proteostasis during mitochondrial dysfunction.

Limitations of this brief

• This Mitos brief is an abstract-level synthesis of a preprint; it is not peer review and not a substitute for reading the full paper.
• Preprint status: findings may change with revision or journal review.
• Effect sizes, n numbers, statistics, and full experimental controls are typically incomplete at abstract resolution.
• Primary source: biorxiv DOI 10.64898/2026.08.10.743879 (posted 2026-08-17).

Open scientific questions

• Which specific experimental panels in the full paper establish the strongest causal claim, and how robust are the controls?
• Are OXPHOS defects primary drivers or secondary consequences of broader cellular stress?
• How do these findings sit relative to prior literature on the same pathway—replication, contradiction, or incremental extension?

Bottom line

For mitochondrial biologists focused on OXPHOS, genetics, this preprint is worth full-text review soon. Abstract-level takeaway: Here, we show that mitochondrial import stress drives widespread rerouting of mitochondrial proteins to the endoplasmic reticulum (ER), with strong enrichment for hydrophobic oxidative phosphorylation (OXPHOS) components. Confirm methods, effect sizes, and controls in the full PDF before citing the result as established.

Bibliographic record

Abstract-based editorial synthesis by Mitos. Not peer review.