PET117 (Protein PET117 homolog, mitochondrial; HGNC:40045; gene MIM 614771) is a small
(81 aa) nucleus-encoded mitochondrial protein that acts as an assembly chaperone for
cytochrome c oxidase (COX / mitochondrial respiratory chain complex IV). It is the human
ortholog of S. cerevisiae PET117, a known COX assembly factor. It is non-catalytic: it
carries no enzyme domain and functions as an assembly/stabilization factor, not an enzyme.
The mature protein is short with a predicted N-terminal mitochondrial transit peptide (aa
1–22) and a single Pfam PET117 domain (PF15786; InterPro IPR031568). AlphaFold/SMR models a
predominantly coiled-coil fold, consistent with a small coiled-coil scaffold/chaperone.
Ortholog prediction + mitochondrial localization (IDA): PET117 (LOC100303755) is the
human ortholog of yeast PET117 ("Assembly of COX"), and GFP-tagged human PET117 co-localizes
with a mitochondrial marker in live HEK293 cells.
PMID:22356826
The same study co-purified the COX assembly factor COX17 with PET117-TAP as bait, linking it
to the COX assembly machinery. PMID:22356826
Role in module-based COX assembly (IDA): In a quantitative-MS reconstruction of the human
COX assembly pathway, PET117 acts together with the highly conserved PET100 chaperone (and the
newly identified MR-1S) to assist COX biogenesis.
PMID:28199844
Abstract-only cache; the annotation is an experimental IDA made by a curator with full-text access.
COX1 synthesis regulation via TACO1 (IDA): PET117 depletion reduces the mitochondrial
oxygen consumption rate and impairs mitochondrial function; PET117 stabilizes the COX1
translational activator TACO1 and prevents its ubiquitination, thereby supporting COX1 (a
mtDNA-encoded core subunit) synthesis.
PMID:37247699
PMID:37247699
Abstract-only cache.
High-throughput mitochondrial proteome (HTP): PET117 is a member of the high-confidence
human mitochondrial proteome. [PMID:34800366 — MS-based mitochondrial proteome inventory]
Disease: Biallelic PET117 variants cause Mitochondrial complex IV deficiency, nuclear
type 19 (MC4DN19; MIM 619063), an autosomal recessive disorder with global developmental
delay, developmental regression, and complex IV deficiency; the reported variant deletes the
C-terminal residues 58–81 (PMID:28386624, not in GOA/cache but recorded in UniProt).
[file:human/PET117/PET117-uniprot.txt "Missing (in MC4DN19)"]
(A pituitary/other phenotype has also been discussed in the broader literature; the
canonical UniProt disease is the MC4DN19 neurodevelopmental phenotype.)
All 8 GOA lines are ACCEPTed:
- GO:0033617 (mito resp chain complex IV assembly) — core BP. Two experimental IDAs
(PMID:28199844, PMID:37247699) plus a PAN-GO IBA converge here.
- GO:0005739 (mitochondrion) — multiple IDA/HTP/IEA/IBA; accepted. The finer inner-membrane
location (GO:0005743) is captured in core_functions.located_in.
No molecular function is asserted: PET117 is non-catalytic and has only chaperone/scaffold
activity; no informative MF term is supported by experimental data (interactions are with
COX17/TACO1 but the only candidate MF would be bare protein binding, which is uninformative
and per policy omitted from core_functions).