id: Q18965 gene_symbol: eat-3 product_type: PROTEIN status: IN_PROGRESS taxon: id: NCBITaxon:6239 label: Caenorhabditis elegans description: EAT-3 is the Caenorhabditis elegans ortholog of mammalian OPA1, a dynamin-family GTPase that promotes mitochondrial inner-membrane fusion and maintains cristae architecture. It has a mitochondrial targeting sequence and conserved GTPase and assembly domains, and acts at the inner membrane with an intermembrane-space-exposed region. Loss of eat-3 causes mitochondrial fragmentation, inner-membrane septae, reduced cristae, slow growth, reduced brood size and increased sensitivity to superoxide-generating paraquat. Genetic suppression and mitochondrial ultrastructure connect these phenotypes to membrane dynamics and oxidative-stress resistance. existing_annotations: - term: id: GO:0003924 label: GTPase activity evidence_type: IBA original_reference_id: GO_REF:0000033 review: summary: EAT-3 retains the dynamin-family GTP-binding and hydrolytic mechanism underlying mitochondrial membrane remodeling. action: ACCEPT reason: The GTPase IBD is at PTN000170013 in PTHR11566. EAT-3 has conserved nucleotide-binding motifs, and primary mutations and intragenic suppressors in its GTPase domain alter and restore biological function (PMID:18454199). Those suppressor experiments are genetic, not direct measurements of rescued enzyme activity; the authors propose restoration of GTP interaction or hydrolysis-associated conformational changes. Broad nucleotide binding and hydrolase annotations remain valid alongside GTPase specificity. supported_by: - reference_id: PMID:18454199 supporting_text: It seems likely that they restore the ability of the G2 threonine to interact properly with GTP or make the conformational changes that occur during GTP hydrolysis. - term: id: GO:0005737 label: cytoplasm evidence_type: IBA original_reference_id: GO_REF:0000033 review: summary: Cytoplasm is an accurate broad compartment for a mitochondrial protein. action: ACCEPT reason: The PTN000170013 cytoplasm IBD does not imply free cytosolic localization. Mitochondria are cytoplasmic organelles, so the experimentally supported mitochondrial and intermembrane-space localizations are compatible with this broad term. The previous objection conflated cytoplasm with cytosol. - term: id: GO:0008053 label: mitochondrial fusion evidence_type: IBA original_reference_id: GO_REF:0000033 review: summary: EAT-3 functions at the mitochondrial inner membrane with a domain exposed to the intermembrane space. action: ACCEPT reason: The fusion/membrane/IMS IBD is at PTN007514526 in PTHR11566. Target genetic and ultrastructural experiments demonstrate disrupted fusion and cristae organization (PMID:18454199), while fractionation and protease protection use EAT-3 as an inner-membrane/IMS marker (PMID:21248201). Target fusion evidence contributing to the PAINT node is legitimate descendant grounding, not circularity. The broader mitochondrial-membrane term remains correct. supported_by: - reference_id: PMID:21248201 supporting_text: We used antibodies against a C. elegans Mff homologue, encoded by the F55F8.6 gene, as a control for proteins exposed to the cytosol (Gandre-Babbe and van der Bliek, 2008) and antibodies against the C. elegans Opa1 homologue EAT-3 (Kanazawa et al., 2008) as a control for proteins exposed to the IMS - term: id: GO:0031966 label: mitochondrial membrane evidence_type: IBA original_reference_id: GO_REF:0000033 review: summary: EAT-3 functions at the mitochondrial inner membrane with a domain exposed to the intermembrane space. action: ACCEPT reason: The fusion/membrane/IMS IBD is at PTN007514526 in PTHR11566. Target genetic and ultrastructural experiments demonstrate disrupted fusion and cristae organization (PMID:18454199), while fractionation and protease protection use EAT-3 as an inner-membrane/IMS marker (PMID:21248201). Target fusion evidence contributing to the PAINT node is legitimate descendant grounding, not circularity. The broader mitochondrial-membrane term remains correct. supported_by: - reference_id: PMID:21248201 supporting_text: We used antibodies against a C. elegans Mff homologue, encoded by the F55F8.6 gene, as a control for proteins exposed to the cytosol (Gandre-Babbe and van der Bliek, 2008) and antibodies against the C. elegans Opa1 homologue EAT-3 (Kanazawa et al., 2008) as a control for proteins exposed to the IMS - term: id: GO:0016559 label: peroxisome fission evidence_type: IBA original_reference_id: GO_REF:0000033 review: summary: The inherited nonmitochondrial function requires assessment beyond the dominant inner-membrane role. action: UNDECIDED reason: The GOA assertion traces to PTN008520527 in PTHR11566. Primary experiments establish mitochondrial targeting, protease-protected localization, inner-membrane fusion and cristae organization. These findings create a mechanistic question about access to cytosolic microtubules or peroxisomes, but do not alone exclude every precursor, processed form or additional context. The previous rejection relied on principal localization and family specialization without resolving inheritance or loss at the relevant ancestral node. Keep the exact inherited claim unresolved after the focused source/target report. The report confirms that PTN000170013 and PTN008520527 are ancestors of OPA1 node PTN007514526, so donor specialization alone does not overturn the ancestral placement. Its missing PH/PRD/GED-domain argument is not a demonstrated requirement for every microtubule interaction or membrane-remodeling mechanism. Rejection does not require a negative capacity assay. Here the ancestry is verified and the proposed domain-loss premise is contradicted; topology remains a strong mechanistic constraint requiring adjudication of inheritance or loss. PMID:32228866 explicitly identifies human OPA1 middle/GED stalk architecture (Fig. 1A and Fig. 3); the report's claimed absence of GED is therefore not a valid family-level premise. This ortholog structure does not itself demonstrate the disputed EAT-3 capacity. propagation_review: root_cause: UNRESOLVED source_entities: - source_id: PANTHER:PTN008520527 source_label: PTN008520527 source_status: UNRESOLVED comment: Actual PAINT IBD recovered. Mitochondrial topology is a constraint to investigate, not by itself proof that the inherited capacity was lost. supported_by: - reference_id: PMID:21248201 supporting_text: MOMA-1 and F55F8.6 proteins are both much more sensitive to proteases than EAT-3 - reference_id: PMID:32228866 supporting_text: OPA1 contains an N-terminal mitochondrial targeting sequence (MTS), a following transmembrane domain (TM), a coiled-coil domain, a highly conserved GTPase domain, a middle domain, and a C-terminal GTPase effector domain (GED). - term: id: GO:0005758 label: mitochondrial intermembrane space evidence_type: IBA original_reference_id: GO_REF:0000033 review: summary: EAT-3 functions at the mitochondrial inner membrane with a domain exposed to the intermembrane space. action: ACCEPT reason: The fusion/membrane/IMS IBD is at PTN007514526 in PTHR11566. Target genetic and ultrastructural experiments demonstrate disrupted fusion and cristae organization (PMID:18454199), while fractionation and protease protection use EAT-3 as an inner-membrane/IMS marker (PMID:21248201). Target fusion evidence contributing to the PAINT node is legitimate descendant grounding, not circularity. The broader mitochondrial-membrane term remains correct. supported_by: - reference_id: PMID:21248201 supporting_text: We used antibodies against a C. elegans Mff homologue, encoded by the F55F8.6 gene, as a control for proteins exposed to the cytosol (Gandre-Babbe and van der Bliek, 2008) and antibodies against the C. elegans Opa1 homologue EAT-3 (Kanazawa et al., 2008) as a control for proteins exposed to the IMS - term: id: GO:0005874 label: microtubule evidence_type: IBA original_reference_id: GO_REF:0000033 review: summary: The inherited nonmitochondrial function requires assessment beyond the dominant inner-membrane role. action: UNDECIDED reason: The GOA assertion traces to PTN000170013 in PTHR11566. Primary experiments establish mitochondrial targeting, protease-protected localization, inner-membrane fusion and cristae organization. These findings create a mechanistic question about access to cytosolic microtubules or peroxisomes, but do not alone exclude every precursor, processed form or additional context. The previous rejection relied on principal localization and family specialization without resolving inheritance or loss at the relevant ancestral node. Keep the exact inherited claim unresolved after the focused source/target report. The report confirms that PTN000170013 and PTN008520527 are ancestors of OPA1 node PTN007514526, so donor specialization alone does not overturn the ancestral placement. Its missing PH/PRD/GED-domain argument is not a demonstrated requirement for every microtubule interaction or membrane-remodeling mechanism. Rejection does not require a negative capacity assay. Here the ancestry is verified and the proposed domain-loss premise is contradicted; topology remains a strong mechanistic constraint requiring adjudication of inheritance or loss. PMID:32228866 explicitly identifies human OPA1 middle/GED stalk architecture (Fig. 1A and Fig. 3); the report's claimed absence of GED is therefore not a valid family-level premise. This ortholog structure does not itself demonstrate the disputed EAT-3 capacity. propagation_review: root_cause: UNRESOLVED source_entities: - source_id: PANTHER:PTN000170013 source_label: PTN000170013 source_status: UNRESOLVED comment: Actual PAINT IBD recovered. Mitochondrial topology is a constraint to investigate, not by itself proof that the inherited capacity was lost. supported_by: - reference_id: PMID:21248201 supporting_text: MOMA-1 and F55F8.6 proteins are both much more sensitive to proteases than EAT-3 - reference_id: PMID:32228866 supporting_text: OPA1 contains an N-terminal mitochondrial targeting sequence (MTS), a following transmembrane domain (TM), a coiled-coil domain, a highly conserved GTPase domain, a middle domain, and a C-terminal GTPase effector domain (GED). - term: id: GO:0008017 label: microtubule binding evidence_type: IBA original_reference_id: GO_REF:0000033 review: summary: The inherited nonmitochondrial function requires assessment beyond the dominant inner-membrane role. action: UNDECIDED reason: The GOA assertion traces to PTN000170013 in PTHR11566. Primary experiments establish mitochondrial targeting, protease-protected localization, inner-membrane fusion and cristae organization. These findings create a mechanistic question about access to cytosolic microtubules or peroxisomes, but do not alone exclude every precursor, processed form or additional context. The previous rejection relied on principal localization and family specialization without resolving inheritance or loss at the relevant ancestral node. Keep the exact inherited claim unresolved after the focused source/target report. The report confirms that PTN000170013 and PTN008520527 are ancestors of OPA1 node PTN007514526, so donor specialization alone does not overturn the ancestral placement. Its missing PH/PRD/GED-domain argument is not a demonstrated requirement for every microtubule interaction or membrane-remodeling mechanism. Rejection does not require a negative capacity assay. Here the ancestry is verified and the proposed domain-loss premise is contradicted; topology remains a strong mechanistic constraint requiring adjudication of inheritance or loss. PMID:32228866 explicitly identifies human OPA1 middle/GED stalk architecture (Fig. 1A and Fig. 3); the report's claimed absence of GED is therefore not a valid family-level premise. This ortholog structure does not itself demonstrate the disputed EAT-3 capacity. propagation_review: root_cause: UNRESOLVED source_entities: - source_id: PANTHER:PTN000170013 source_label: PTN000170013 source_status: UNRESOLVED comment: Actual PAINT IBD recovered. Mitochondrial topology is a constraint to investigate, not by itself proof that the inherited capacity was lost. supported_by: - reference_id: PMID:21248201 supporting_text: MOMA-1 and F55F8.6 proteins are both much more sensitive to proteases than EAT-3 - reference_id: PMID:32228866 supporting_text: OPA1 contains an N-terminal mitochondrial targeting sequence (MTS), a following transmembrane domain (TM), a coiled-coil domain, a highly conserved GTPase domain, a middle domain, and a C-terminal GTPase effector domain (GED). - term: id: GO:0000166 label: nucleotide binding evidence_type: IEA original_reference_id: GO_REF:0000043 review: summary: EAT-3 retains the dynamin-family GTP-binding and hydrolytic mechanism underlying mitochondrial membrane remodeling. action: ACCEPT reason: The GTPase IBD is at PTN000170013 in PTHR11566. EAT-3 has conserved nucleotide-binding motifs, and primary mutations and intragenic suppressors in its GTPase domain alter and restore biological function (PMID:18454199). Those suppressor experiments are genetic, not direct measurements of rescued enzyme activity; the authors propose restoration of GTP interaction or hydrolysis-associated conformational changes. Broad nucleotide binding and hydrolase annotations remain valid alongside GTPase specificity. supported_by: - reference_id: PMID:18454199 supporting_text: It seems likely that they restore the ability of the G2 threonine to interact properly with GTP or make the conformational changes that occur during GTP hydrolysis. - term: id: GO:0003924 label: GTPase activity evidence_type: IEA original_reference_id: GO_REF:0000002 review: summary: EAT-3 retains the dynamin-family GTP-binding and hydrolytic mechanism underlying mitochondrial membrane remodeling. action: ACCEPT reason: The GTPase IBD is at PTN000170013 in PTHR11566. EAT-3 has conserved nucleotide-binding motifs, and primary mutations and intragenic suppressors in its GTPase domain alter and restore biological function (PMID:18454199). Those suppressor experiments are genetic, not direct measurements of rescued enzyme activity; the authors propose restoration of GTP interaction or hydrolysis-associated conformational changes. Broad nucleotide binding and hydrolase annotations remain valid alongside GTPase specificity. supported_by: - reference_id: PMID:18454199 supporting_text: It seems likely that they restore the ability of the G2 threonine to interact properly with GTP or make the conformational changes that occur during GTP hydrolysis. - term: id: GO:0005525 label: GTP binding evidence_type: IEA original_reference_id: GO_REF:0000120 review: summary: EAT-3 retains the dynamin-family GTP-binding and hydrolytic mechanism underlying mitochondrial membrane remodeling. action: ACCEPT reason: The GTPase IBD is at PTN000170013 in PTHR11566. EAT-3 has conserved nucleotide-binding motifs, and primary mutations and intragenic suppressors in its GTPase domain alter and restore biological function (PMID:18454199). Those suppressor experiments are genetic, not direct measurements of rescued enzyme activity; the authors propose restoration of GTP interaction or hydrolysis-associated conformational changes. Broad nucleotide binding and hydrolase annotations remain valid alongside GTPase specificity. supported_by: - reference_id: PMID:18454199 supporting_text: It seems likely that they restore the ability of the G2 threonine to interact properly with GTP or make the conformational changes that occur during GTP hydrolysis. - term: id: GO:0005743 label: mitochondrial inner membrane evidence_type: IEA original_reference_id: GO_REF:0000044 review: summary: EAT-3 functions at the mitochondrial inner membrane with a domain exposed to the intermembrane space. action: ACCEPT reason: The fusion/membrane/IMS IBD is at PTN007514526 in PTHR11566. Target genetic and ultrastructural experiments demonstrate disrupted fusion and cristae organization (PMID:18454199), while fractionation and protease protection use EAT-3 as an inner-membrane/IMS marker (PMID:21248201). Target fusion evidence contributing to the PAINT node is legitimate descendant grounding, not circularity. The broader mitochondrial-membrane term remains correct. supported_by: - reference_id: PMID:21248201 supporting_text: We used antibodies against a C. elegans Mff homologue, encoded by the F55F8.6 gene, as a control for proteins exposed to the cytosol (Gandre-Babbe and van der Bliek, 2008) and antibodies against the C. elegans Opa1 homologue EAT-3 (Kanazawa et al., 2008) as a control for proteins exposed to the IMS - term: id: GO:0005758 label: mitochondrial intermembrane space evidence_type: IEA original_reference_id: GO_REF:0000044 review: summary: EAT-3 functions at the mitochondrial inner membrane with a domain exposed to the intermembrane space. action: ACCEPT reason: The fusion/membrane/IMS IBD is at PTN007514526 in PTHR11566. Target genetic and ultrastructural experiments demonstrate disrupted fusion and cristae organization (PMID:18454199), while fractionation and protease protection use EAT-3 as an inner-membrane/IMS marker (PMID:21248201). Target fusion evidence contributing to the PAINT node is legitimate descendant grounding, not circularity. The broader mitochondrial-membrane term remains correct. supported_by: - reference_id: PMID:21248201 supporting_text: We used antibodies against a C. elegans Mff homologue, encoded by the F55F8.6 gene, as a control for proteins exposed to the cytosol (Gandre-Babbe and van der Bliek, 2008) and antibodies against the C. elegans Opa1 homologue EAT-3 (Kanazawa et al., 2008) as a control for proteins exposed to the IMS - term: id: GO:0006915 label: apoptotic process evidence_type: IEA original_reference_id: GO_REF:0000043 review: summary: Direct C. elegans assays argue against transferring the canonical OPA1 apoptotic role to EAT-3. action: REMOVE reason: This decision rests on experiments, not absence of target publications or mitochondrial specialization. PMID:18454199 finds no increase in dying embryonic cells and no rescue of growth or brood-size defects by ced-3/ced-4 loss. PMID:18722182 additionally tests developmental cell-corpse profiles, inappropriate pharyngeal-cell survival and a sensitized ced-3 background without detecting an eat-3-dependent death effect. These data oppose the inherited canonical apoptotic role represented by the keyword mapping, while not proving that EAT-3 can never affect death under any untested stress. supported_by: - reference_id: PMID:18722182 supporting_text: Analysis of fzo-1(tm1133); ced-3(n2438) animals and eat-3(ad426); ced-3(n2438) animals did not reveal a significant decrease or increase in the number of extra cells compared with ced-3(n2438) animals - term: id: GO:0008289 label: lipid binding evidence_type: IEA original_reference_id: GO_REF:0000043 review: summary: Lipid interaction is a supported family mechanism of OPA1/Mgm1-type membrane remodeling. action: ACCEPT reason: Retain this inferred EAT-3 lipid-binding activity while clearly distinguishing ortholog biochemistry from direct worm assays. PMID:19703904 maps lipid-binding determinants in yeast Mgm1 using liposome association, activity and complementation experiments; PMID:28628083 reconstitutes human OPA1-cardiolipin fusion. These are relevant support for conservation of the broad function. The old added PMID:23226476 instead concerns hCG-driven mouse reproductive dysfunction and tumorigenesis, and is withdrawn as a wrong supporting identifier. supported_by: - reference_id: PMID:19703904 supporting_text: 'Here, we demonstrate that s-Mgm1 binds to a mixture of phospholipids characteristic of the mitochondrial inner membrane.' - reference_id: PMID:28628083 supporting_text: 'L-OPA1 and cardiolipin (CL) cooperate in heterotypic mitochondrial IM fusion.' - term: id: GO:0016787 label: hydrolase activity evidence_type: IEA original_reference_id: GO_REF:0000043 review: summary: EAT-3 retains the dynamin-family GTP-binding and hydrolytic mechanism underlying mitochondrial membrane remodeling. action: ACCEPT reason: The GTPase IBD is at PTN000170013 in PTHR11566. EAT-3 has conserved nucleotide-binding motifs, and primary mutations and intragenic suppressors in its GTPase domain alter and restore biological function (PMID:18454199). Those suppressor experiments are genetic, not direct measurements of rescued enzyme activity; the authors propose restoration of GTP interaction or hydrolysis-associated conformational changes. Broad nucleotide binding and hydrolase annotations remain valid alongside GTPase specificity. supported_by: - reference_id: PMID:18454199 supporting_text: It seems likely that they restore the ability of the G2 threonine to interact properly with GTP or make the conformational changes that occur during GTP hydrolysis. - term: id: GO:0005739 label: mitochondrion evidence_type: IDA original_reference_id: PMID:21248201 review: summary: EAT-3 is experimentally recovered in the mitochondrial fraction. action: ACCEPT reason: 'Although the paper foregrounds MOMA-1, PMID:21248201 explicitly assays EAT-3 as a compartment control: 88% is in the mitochondrial pellet, and it is protected from protease in intact mitochondria. This is direct evidence on EAT-3, not a citation misattributed from the protein named in the title.' supported_by: - reference_id: PMID:21248201 supporting_text: 'The distributions were quantified with densitometry of P2 and S2 fractions: 88% of EAT-3, 12% of tubulin, and 98% of MOMA-1 is in the mitochondrial pellet.' - term: id: GO:0002119 label: nematode larval development evidence_type: IGI original_reference_id: PMID:18454199 review: summary: eat-3 mutants have slow development and growth defects. This is a phenotypic consequence of mitochondrial dysfunction rather than a core function. action: KEEP_AS_NON_CORE reason: While eat-3 mutants do have developmental defects (slow growth, delayed development), these are secondary consequences of impaired mitochondrial function rather than a direct role in development. The core function is mitochondrial inner membrane fusion. supported_by: - reference_id: PMID:18454199 supporting_text: Worms injected with eat-3 dsRNA give viable progeny but their brood size is reduced... The F1 worms remain small, are sluggish and develop slowly. - term: id: GO:0040014 label: regulation of multicellular organism growth evidence_type: IMP original_reference_id: PMID:18454199 review: summary: eat-3 mutants show growth defects, but this is a pleiotropic consequence of mitochondrial dysfunction rather than a direct regulatory role in growth. action: KEEP_AS_NON_CORE reason: eat-3 loss of function causes slow growth and small body size, but this is due to impaired mitochondrial function (oxidative phosphorylation defects) rather than a direct role in regulating organismal growth. The growth defects are consistent with metabolic insufficiency. supported_by: - reference_id: PMID:18454199 supporting_text: eat-3 RNAi worms rarely reach 0.5 mm, consistent with a previous study showing that the eat-3(ad426) mutant also remains small... developmental decisions are normal, but the rate of development is greatly reduced as one might expect from a general decrease in metabolic activity. - term: id: GO:0040014 label: regulation of multicellular organism growth evidence_type: IGI original_reference_id: PMID:18454199 review: summary: This is a duplicate annotation with IGI evidence, showing genetic interactions affecting growth. Same reasoning as above - secondary phenotype. action: KEEP_AS_NON_CORE reason: Growth phenotype is a secondary consequence of mitochondrial dysfunction, not a core regulatory function. supported_by: - reference_id: PMID:18454199 supporting_text: the phenotypes of eat-3 mutants are consistent with defects in oxidative phosphorylation. - term: id: GO:0008053 label: mitochondrial fusion evidence_type: IMP original_reference_id: PMID:18722182 review: summary: The cell-death study directly examines mitochondrial fusion phenotypes in eat-3 mutants. action: ACCEPT reason: PMID:18722182 includes mitochondrial staining and electron microscopy of eat-3(ad426) and eat-3(tm1107) embryos. Fragmentation and altered cristae independently support the fusion annotation; the abstract focus on apoptosis does not weaken these full-text target experiments. supported_by: - reference_id: PMID:18722182 supporting_text: Conversely, mitochondria appeared highly fragmented in fzo-1(tm1133), eat-3(ad426) and eat-3(tm1107) embryos - term: id: GO:0000303 label: response to superoxide evidence_type: IMP original_reference_id: PMID:18454199 review: summary: eat-3 mutants are hypersensitive to paraquat and show induction of SOD-2. This is a stress response consequence of mitochondrial dysfunction. action: KEEP_AS_NON_CORE reason: eat-3 mutants show hypersensitivity to paraquat (superoxide) and compensatory induction of SOD-2, but this is a consequence of mitochondrial dysfunction leading to increased ROS production, not a primary function in oxidative stress response. supported_by: - reference_id: PMID:18454199 supporting_text: eat-3 mutants are hypersensitive to paraquat, which promotes damage by free radicals, and they are sensitive to loss of the mitochondrial superoxide dismutase sod-2. We conclude that free radicals contribute to the pathology of C. elegans eat-3 mutants. - reference_id: PMID:18454199 supporting_text: Fe/Mn-SOD expression is induced more than two-fold in eat-3(ad426) animals... This induction is almost entirely attributable to SOD-2 - term: id: GO:0007005 label: mitochondrion organization evidence_type: IMP original_reference_id: PMID:18454199 review: summary: EAT-3 promotes mitochondrial inner-membrane fusion and maintains cristae architecture. action: ACCEPT reason: 'PMID:18454199 combines target genetics, rescue and electron microscopy: mutant mitochondria fragment, contain inner-membrane septae and have reduced cristae. The phenotype and conserved OPA1/Mgm1 mechanism support direct membrane-organization work rather than only an upstream requirement for mitochondrial health. No respiratory-chain catalytic activity is inferred.' supported_by: - reference_id: PMID:18454199 supporting_text: "Electron microscopy shows that \nthe matrices of fragmented mitochondria in eat-3 mutants are divided by inner \nmembrane septae, suggestive of a specific defect in fusion of the mitochondrial \ninner membrane." - term: id: GO:0008053 label: mitochondrial fusion evidence_type: IMP original_reference_id: PMID:18454199 review: summary: EAT-3 promotes mitochondrial inner-membrane fusion and maintains cristae architecture. action: ACCEPT reason: 'PMID:18454199 combines target genetics, rescue and electron microscopy: mutant mitochondria fragment, contain inner-membrane septae and have reduced cristae. The phenotype and conserved OPA1/Mgm1 mechanism support direct membrane-organization work rather than only an upstream requirement for mitochondrial health. No respiratory-chain catalytic activity is inferred.' supported_by: - reference_id: PMID:18454199 supporting_text: "Electron microscopy shows that \nthe matrices of fragmented mitochondria in eat-3 mutants are divided by inner \nmembrane septae, suggestive of a specific defect in fusion of the mitochondrial \ninner membrane." - term: id: GO:0035264 label: multicellular organism growth evidence_type: IMP original_reference_id: PMID:18454199 review: summary: eat-3 mutants show reduced body size and growth, a consequence of mitochondrial dysfunction. action: KEEP_AS_NON_CORE reason: Growth defects are a secondary phenotype of mitochondrial dysfunction, not a core function of EAT-3. supported_by: - reference_id: PMID:18454199 supporting_text: The F1 worms remain small, are sluggish and develop slowly... eat-3 RNAi worms rarely reach 0.5 mm references: - id: GO_REF:0000002 title: Gene Ontology annotation through association of InterPro records with GO terms findings: [] - id: GO_REF:0000033 title: Annotation inferences using phylogenetic trees findings: [] - id: GO_REF:0000043 title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping findings: [] - id: GO_REF:0000044 title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping findings: [] - id: GO_REF:0000120 title: Combined Automated Annotation using Multiple IEA Methods findings: [] - id: PMID:18454199 title: The C. elegans Opa1 homologue EAT-3 is essential for resistance to free radicals. findings: - statement: EAT-3 is the C. elegans ortholog of OPA1/Mgm1, with conserved dynamin domains supporting_text: 'Similar to yeast Mgm1 and mammalian Opa1, this C. elegans protein has a putative mitochondrial targeting sequence followed by domains that are typical of dynamin family members: a conserved GTPase domain, a middle domain and a GED or assembly domain' - statement: eat-3 mutations cause mitochondrial fragmentation with inner membrane septae supporting_text: We find that mutations in the C. elegans eat-3 locus cause mitochondria to fragment in agreement with the mutant phenotypes observed in yeast and mammalian cells. Electron microscopy shows that the matrices of fragmented mitochondria in eat-3 mutants are divided by inner membrane septae, suggestive of a specific defect in fusion of the mitochondrial inner membrane. - statement: Cristae length is reduced by 66.2% after normalization to inner-boundary membrane length. supporting_text: There is, however, still a 66.2% decrease of total cristae length when normalized with the lengths of inner boundary membranes or a 70.3% decrease when normalized with the surface area of the mitochondrial section. - statement: eat-3 mutants are hypersensitive to paraquat and induce SOD-2 supporting_text: eat-3 mutants are hypersensitive to paraquat, which promotes damage by free radicals, and they are sensitive to loss of the mitochondrial superoxide dismutase sod-2. We conclude that free radicals contribute to the pathology of C. elegans eat-3 mutants. - statement: drp-1 mutations suppress eat-3 phenotypes supporting_text: We conclude that a functioning mitochondrial division apparatus is required for the mitochondrial fragmentation induced by mutant eat-3. - statement: ced-3/ced-4 mutations do not suppress eat-3 phenotypes supporting_text: Although mammalian Opa1 is antiapoptotic, mutations in the canonical C. elegans cell death genes ced-3 and ced-4 do not suppress the slow growth and small broodsize phenotypes of eat-3 mutants. - id: PMID:18722182 title: Caenorhabditis elegans drp-1 and fis-2 regulate distinct cell-death execution pathways downstream of ced-3 and independent of ced-9. findings: - statement: eat-3 and fzo-1 are not required for apoptosis activation in C. elegans supporting_text: Here we report that profusion genes fzo-1 and eat-3 or the profission gene drp-1 are not required for apoptosis activation in C. elegans. - id: PMID:21248201 title: A novel mitochondrial outer membrane protein, MOMA-1, that affects cristae morphology in Caenorhabditis elegans. findings: - statement: EAT-3 co-fractionates with mitochondria (88% in mitochondrial pellet) supporting_text: 'The distributions were quantified with densitometry of P2 and S2 fractions: 88% of EAT-3, 12% of tubulin, and 98% of MOMA-1 is in the mitochondrial pellet.' - statement: EAT-3 is protease-protected in intact mitochondria supporting_text: MOMA-1 is digested when no detergent is added, like MFF-1, while EAT-3 and F1β are protease protected. - statement: EAT-3 used as IMS marker in protease protection experiments supporting_text: antibodies against the C. elegans Opa1 homologue EAT-3 (Kanazawa et al., 2008) as a control for proteins exposed to the IMS - id: file:worm/eat-3/eat-3-deep-research-falcon.md title: Deep research review of eat-3 gene function findings: [] - id: PMID:19703904 title: Phospholipid association is essential for dynamin-related protein Mgm1 to function in mitochondrial membrane fusion. - id: PMID:28628083 title: Molecular basis of selective mitochondrial fusion by heterotypic action between OPA1 and cardiolipin. - id: file:worm/eat-3/eat-3-hypotheses/microtubule-and-peroxisome-capacities/openscientist.md title: 'EAT-3: microtubule and peroxisome capacities' reference_review: relevance: HIGH correctness: DISPUTED review_notes: Full report read. Correctly emphasizes mitochondrial fusion/topology and recovers the relevant ancestral nodes. However, both challenged nodes are ancestors of the OPA1 node, not transfers from an exclusively separate DRP1 clade. Missing conventional dynamin modules do not establish loss of all binding or process capacities. No executable tree/domain artifact was supplied. Full PMID:32228866 explicitly describes the OPA1 middle/GED stalk, contradicting the report's claimed missing GED module. - id: PMID:32228866 title: Cryo-EM structures of S-OPA1 reveal its interactions with membrane and changes upon nucleotide binding. core_functions: - molecular_function: id: GO:0003924 label: GTPase activity description: Uses a conserved dynamin-family GTPase mechanism to remodel mitochondrial inner membranes, supporting fusion and cristae architecture. Target GTPase-domain mutations and intragenic suppressors establish the biological importance of this domain; biochemical restoration of hydrolysis was not directly measured in the genetic rescue study. directly_involved_in: - id: GO:1990627 label: mitochondrial inner membrane fusion locations: - id: GO:0005743 label: mitochondrial inner membrane - id: GO:0005758 label: mitochondrial intermembrane space supported_by: - reference_id: PMID:18454199 supporting_text: It seems likely that they restore the ability of the G2 threonine to interact properly with GTP or make the conformational changes that occur during GTP hydrolysis. - reference_id: PMID:18454199 supporting_text: "Electron microscopy shows that \nthe matrices of fragmented mitochondria in eat-3 mutants are divided by inner \nmembrane septae, suggestive of a specific defect in fusion of the mitochondrial \ninner membrane." suggested_questions: - question: Does EAT-3 have proteolytic processing similar to mammalian OPA1 (l-OPA1/s-OPA1 forms)? - question: What is the relationship between EAT-3 and cristae junction formation? - question: Does EAT-3 interact with cardiolipin or other mitochondrial lipids? suggested_experiments: - description: Determine if EAT-3 exists in long and short forms like mammalian OPA1 - description: Test for physical interaction between EAT-3 and IMMT-1 (mitofilin) - description: Measure in vitro GTPase activity of purified EAT-3 tags: - caeel-mitophagy