coq8

Summary: TAS citing the in vitro COQ metabolon reconstruction, in which a reconstructed animal COQ8B phosphorylated COQ3 and showed only basal ATPase activity. COQ8-family UbiB proteins are atypical kinase-like ATPases whose physiological substrate is unresolved, and protein kinase activity has not been tested for S. pombe Coq8.

Reason: PomBase TAS (PMID:38425362). The cited paper does show protein phosphorylation (COQ3 by animal COQ8B, in vitro), so the term is not baseless. But this is real in vitro activity of unknown physiological relevance, from an animal protein, not S. pombe. UniProt's curated function (by similarity to human COQ8A/COQ8B) records that the substrate specificity is unclear, with protein-kinase and small-molecule or lipid-kinase models both proposed. Asserting protein kinase activity for S. pombe Coq8 therefore over-reaches the evidence. The human COQ8B review keeps the IDA row from the same paper as non-core because the assay was on that protein; here the statement is transferred to a protein never assayed, so MARK_AS_OVER_ANNOTATED. Yeast Coq8 shows ATPase but not trans protein kinase activity (PMID:27499294).

Summary: ORFeome YFP screen: mitochondrion.

Reason: PomBase HDA from the ORFeome YFP screen. Hayashi et al. state that Coq8 was not among the proteins localised in that screen (PMID:24911838), so the provenance of this HDA cannot be checked from the cached abstract; the mitochondrial location itself is established by Coq8-GFP (PMID:24911838). Accepted on the location, without overruling the curator on the dataset; a question is recorded.

Summary: Mitochondrial localisation of the tagged protein.

Reason: Coq8-GFP expressed in the corresponding deletion strain localises to MitoTracker-stained mitochondria (PMID:24911838). Whole-organelle co-staining: ACCEPT at the root organelle term.

Summary: UniProt/ARBA location mapping; consistent.

Reason: UniProt SubCell mapping (GO_REF:0000044). Mitochondrial location is shown on the target: a Coq8-GFP fusion co-localised with MitoTracker-stained mitochondria (PMID:24911838), which UniProt curates as experimental. Root organelle term kept.

Summary: abc1Sp/coq8 complements the S. cerevisiae abc1 (coq8) mutant (PMID:8668131).

Reason: The S. pombe cDNA was cloned by complementing the respiratory defect of S. cerevisiae abc1, whose product is the CoQ-pathway Coq8 (PMID:8668131), and the S. pombe disruption is rescued by S. cerevisiae ABC1. Cross-species complementation of a CoQ-deficient mutant supports the process; consistent with the IMP rows. Core process.

Summary: PAINT inference; ubiquinone biosynthesis step.

Reason: IBA from PAINT node PTN000059692 (PTHR43851, GO_REF:0000033), of which coq8 is a seed. Shown on the target: the S. pombe abc1Sp/coq8 defective strain makes no UQ-10 (PMID:14695938), and UniProt curates the ubiquinone biosynthesis pathway with experimental evidence (PMID:24911838). The IBA adds that the role is inherited across the COQ8/ADCK family.

Summary: Mapping; consistent.

Reason: UniPathway mapping (GO_REF:0000041). Same claim as the IMP, EXP and IBA rows: the S. pombe abc1Sp/coq8 defective strain makes no UQ-10 (PMID:14695938), and UniProt curates the pathway with experimental evidence.

Summary: abc1Sp/coq8 mutants make no UQ-10.

Reason: The abc1Sp/coq8 defective strain makes no UQ-10 and shows the CoQ-deficient phenotypes (PMID:14695938). Coq8 acts within the CoQ synthome as a UbiB-family ATPase (by homology), so it contributes to the work of the process rather than only being required for it. Core process.

Summary: abc1Sp/coq8 mutants make no UQ-10.

Reason: The coq8 deletion lacks CoQ10, and S. pombe coq8 fully and human COQ8A/ADCK3 partly restore it (PMID:24911838). Core process.

Summary: Peripheral component on the matrix side of the inner membrane, where the CoQ synthome assembles.

Reason: PomBase ISO from S. cerevisiae Coq8 (GO_REF:0000024). ISO transfer from S. cerevisiae Coq8 (SGD:S000003087). The sub-compartment evidence is the ortholog's: Coq8p fractionates as a peripheral membrane protein on the matrix side of the inner membrane (PMID:21296186, S. cerevisiae). In S. pombe only mitochondrial localisation is shown (Coq8-GFP, PMID:24911838); the matrix-side placement is accepted as a well-grounded ortholog inference, consistent with the CoQ synthome being matrix-facing.

Summary: ATPase activity of the UbiB-family Coq8 proteins, shown for S. cerevisiae Coq8 and inferred for S. pombe Coq8.

Reason: S. cerevisiae Coq8 hydrolyses ATP in vitro, an activity enhanced by the UbiB-specific KxGQ motif, while trans protein kinase activity is not detected (PMID:27499294); human COQ8A/B carry the same activity, and the human COQ8B and S. cerevisiae COQ8 reviews make it the core function. S. pombe Coq8 is a UbiB/ADCK-family member and human COQ8A/ADCK3 partially complements the S. pombe deletion (PMID:24911838). No S. pombe ATPase assay exists, so the row is by sequence similarity (ISS); it matches the module's Coq8 annoton (GO:0016887). No GO process is added.