Nature - 2019.08.29

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nature research | reporting summary

October 2018

For a reference copy of the document with all sections, see nature.com/documents/nr-reporting-summary-flat.pdf

Life sciences study design

All studies must disclose on these points even when the disclosure is negative.

Sample size No a priori calculations were performed. Sample size was chosen based on previous experience with similar measurements.

Data exclusions No data were excluded from the analyses.

Replication Experiments were repeated multiple times, as detailed in the text, figure legends or Methods section.There were no attempts at replication

that failed.

Randomization Samples and animals were randomly divided into experimental groups.

Blinding Analyses were not blinded because experiments were performed and analyzed by the same researchers.

Reporting for specific materials, systems and methods

We require information from authors about some types of materials, experimental systems and methods used in many studies. Here, indicate whether each material,

system or method listed is relevant to your study. If you are not sure if a list item applies to your research, read the appropriate section before selecting a response.

Materials & experimental systems

n/a Involved in the study

Antibodies

Eukaryotic cell lines

Palaeontology

Animals and other organisms

Human research participants

Clinical data

Methods

n/a Involved in the study

ChIP-seq

Flow cytometry

MRI-based neuroimaging

Antibodies

Antibodies used The following primary antibodies were used: anti-MITOK-C-term (1:1000, Sigma HPA011408), anti-MITOK-N-term (1:10000,

Sigma HPA010980), anti-MCU (1:1000, Sigma HPA016480), anti-MICU1 (1:1000, Sigma HPA037480), anti-HSP60 (1:5000, Santa

Cruz sc-1052), anti-OPA1 (1:1000, BD biosciences 612606), anti-MITOSUR (1:1000, Abcam ab182662), anti-OXPHOS (1:1000,

Abcam ab110413), anti-TOM20 (1:10000, Santa Cruz sc-11415), anti-Flag (1:1000, Cell Signaling #2368).

Validation MITOK antibodies are validate here: https://www.proteinatlas.org/ENSG00000164051-CCDC51/antibody

MITOK antibodies were also validated in this study using overexpression and knock-out studies

MCU antibody (Sigma HPA016480) validation data are here: https://www.proteinatlas.org/ENSG00000156026-MCU/antibody

MICU1 antibody (igma HPA037480) validation data are here: https://www.proteinatlas.org/ENSG00000107745-MICU1/antibody

HSP60 antibody (Santa Cruz sc-1052) validation data are here: https://www.scbt.com/scbt/product/hsp-60-antibody-n-20

Monoclonal OPA1 (Clone 18) antibody from BD (612606) has been used in many publications

MITOSUR antibody (Abcam ab182662) was validated through overexpression experiments. This product is now discontinued.

Total OXPHOS Rodent WB Antibody Cocktail (ab110413) validation data are here: https://www.abcam.com/total-oxphos-rodent-

wb-antibody-cocktail-ab110413-references.html#top-0

TOM20 antibody (Santa Cruz sc-11415) validation data are here: https://www.scbt.com/scbt/product/tom20-antibody-fl-145

Flag antibody (Cell Signaling #2368) validation data can be found here: https://www.cellsignal.com/products/primary-antibodies/

dykddddk-tag-antibody-binds-to-same-epitope-as-sigma-s-anti-flag-m2-antibody/2368

Eukaryotic cell lines

Policy information about cell lines

Cell line source(s) HeLa cells were purchased from ATCC: http://www.lgcstandards-atcc.org/products/all/CCL-2.aspx

Authentication Cells were authenticated by the commercial source

Mycoplasma contamination Cell lines are tested for mycoplasma contamination every six months using MycoAlert Kit (Promega). Cell lines resulted

"negative" or "bordeline".

Commonly misidentified lines

(See ICLAC register)

No commonly misidentified cell lines were used.