Identity. UniProt A8MTT3 (CEBOS_HUMAN), Protein CEBPZOS, 80 aa, PE1. Gene is on the
strand opposite CEBPZ (HGNC alias CEBPZ-AS1, "CEBPZ opposite strand"). The protein is the
canonical product of its own gene (own UniProt accession and HGNC symbol), so the normal
genes/human/CEBPZOS/ folder is correct; it is not an alternative ORF of CEBPZ.
Predicted single transmembrane helix at residues 15-32 (UniProt FT TRANSMEM, ECO:0000255);
sequence MARTLEPLAKKIFKGVLVAELVGVFGAYFLFSKMHTSQDFRQTMSKKYPFILEVYYKSTEKSGMYGIRELDQKTWLNSKN.
Family: InterPro IPR037764 (CEBPZOS), PANTHER PTHR38001 "PROTEIN CEBPZOS"; no known domain.
Conservation. Conserved to Drosophila: fly CG42371 is listed as the CEBPZOS ortholog
PMID:37889754.
Localization (the only direct human evidence).
- Identified in the IMS-APEX proximity proteome in HEK293T and validated as a new
mitochondrial protein [PMID:25002142 "we have identified 9 novel mitochondrial proteins that we validated by imaging or western blotting"; "three proteins of unknown function (A8MTT3, C1orf163, and CCDC127)"].
IMS-APEX labels proteins exposed to the IMS, consistent with a membrane protein with an
IMS-facing segment; which membrane (inner vs outer) is not resolved.
- In MitoCoP (high-confidence mitochondrial proteome; PMID:34800366) — basis of the
FlyBase HTP row. The cached text does not name CEBPZOS (in supplementary data); GOA row
is consistent with the APEX evidence.
- HeLa "dark mitochondrial proteome" table lists NX_A8MTT3-1 Protein CEBPZOS as known,
sub-mitochondrial location IMS (PMID:32195257); this is a compiled annotation table rather than new localization data.
Function. No direct mechanistic study found. PubMed searches (CEBPZOS, CEBPZ opposite
strand, CEBPZ-AS1) return only 4 papers, all transcriptomic/prognostic signatures
(HCC prognosis models PMID:39349287, 37305349, 35602603; teriparatide MSC lncRNA
screen PMID:40609214) that treat CEBPZOS as a transcript, not as a protein. PMC full-text
mentions:
- Upregulated in HEK293 cells after EtBr-induced mtDNA depletion; considered but not
pursued PMID:31226201.
- Fly CG42371 KO viable on normal food but low viability on high-salt (2 alleles) and
high-fat (1 allele) food PMID:37889754.
- I could NOT find any paper establishing CEBPZOS as a regulator of the integrated stress
response or as a respiratory-complex assembly factor. The MICROPROTEINS project table
groups CEBPZOS with "mitochondrial assembly factors", but I found no evidence for that
placement; it should be treated as unverified.
Conclusion. Function unknown. Solid evidence: mitochondrial, membrane-integrated,
IMS-exposed. All three GOA rows (CC only) are correct; no MF/BP can be supported. No NEW.