MDJ1 encodes the major mitochondrial matrix DnaJ/Hsp40 cochaperone for the mtHsp70 Ssc1 system. Mdj1 stimulates Hsp70-dependent folding/refolding cycles, protects mitochondrial matrix proteins from misfolding and heat-induced aggregation, and is enriched at mitochondrial nucleoids where it supports maintenance of functional mitochondrial DNA.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Manual review: cytoplasm may be context-dependent or peripheral for MDJ1. Reason: Kept as non-core to preserve potentially valid context-specific annotation without elevating it to core function. |
| GO:0042026 protein refolding | IBA GO_REF:0000033 | ACCEPT | Summary: Manual review: protein refolding is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. Supporting Evidence: file:yeast/MDJ1/MDJ1-deep-research-falcon.md Mdj1 participates in **de novo folding** and **protection of mitochondrial proteins against heat-induced unfolding/aggregation** |
| GO:0051082 unfolded protein binding | IBA GO_REF:0000033 | MODIFY | Summary: Manual review: unfolded protein binding is better represented by a more specific replacement term for MDJ1. Reason: Modified to align with current curation guidance and improve term specificity. Proposed replacements: protein folding chaperone |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | MODIFY | Summary: Manual review: ATP binding is likely an automated over-annotation for MDJ1; ATPase activator activity captures the supported biology. Reason: Mdj1 is a J-domain cochaperone that stimulates ATP hydrolysis by mitochondrial Hsp70 Ssc1 rather than an ATP-binding protein itself. Proposed replacements: ATPase activator activity Supporting Evidence: file:yeast/MDJ1/MDJ1-deep-research-falcon.md a J-protein stimulates Hsp70 ATP hydrolysis |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Manual review: mitochondrion may be context-dependent or peripheral for MDJ1. Reason: Kept as non-core to preserve potentially valid context-specific annotation without elevating it to core function. |
| GO:0006457 protein folding | IEA GO_REF:0000002 | ACCEPT | Summary: Manual review: protein folding is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0008270 zinc ion binding | IEA GO_REF:0000043 | ACCEPT | Summary: Manual review: zinc ion binding is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0009408 response to heat | IEA GO_REF:0000002 | ACCEPT | Summary: Manual review: response to heat is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0031072 heat shock protein binding | IEA GO_REF:0000002 | ACCEPT | Summary: Manual review: heat shock protein binding is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0046872 metal ion binding | IEA GO_REF:0000043 | ACCEPT | Summary: Manual review: metal ion binding is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0051082 unfolded protein binding | IEA GO_REF:0000002 | MODIFY | Summary: Manual review: unfolded protein binding is better represented by a more specific replacement term for MDJ1. Reason: Modified to align with current curation guidance and improve term specificity. Proposed replacements: protein folding chaperone |
| GO:0005515 protein binding | IPI PMID:16554755 Global landscape of protein complexes in the yeast Saccharom... | MARK AS OVER ANNOTATED | Summary: Manual review: protein binding is too generic or over-extended for MDJ1. Reason: Marked over-annotated because more specific terms capture the biology more accurately. |
| GO:0005515 protein binding | IPI PMID:19536198 An atlas of chaperone-protein interactions in Saccharomyces ... | MARK AS OVER ANNOTATED | Summary: Manual review: protein binding is too generic or over-extended for MDJ1. Reason: Marked over-annotated because more specific terms capture the biology more accurately. |
| GO:0005515 protein binding | IPI PMID:27107014 An inter-species protein-protein interaction network across ... | MARK AS OVER ANNOTATED | Summary: Manual review: protein binding is too generic or over-extended for MDJ1. Reason: Marked over-annotated because more specific terms capture the biology more accurately. |
| GO:0008270 zinc ion binding | RCA PMID:30358795 The cellular economy of the Saccharomyces cerevisiae zinc pr... | ACCEPT | Summary: Manual review: zinc ion binding is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0005739 mitochondrion | HDA PMID:24769239 Quantitative variations of the mitochondrial proteome and ph... | KEEP AS NON CORE | Summary: Manual review: mitochondrion may be context-dependent or peripheral for MDJ1. Reason: Kept as non-core to preserve potentially valid context-specific annotation without elevating it to core function. |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | KEEP AS NON CORE | Summary: Manual review: mitochondrion may be context-dependent or peripheral for MDJ1. Reason: Kept as non-core to preserve potentially valid context-specific annotation without elevating it to core function. |
| GO:0001671 ATPase activator activity | IDA PMID:9973563 Two distinct mechanisms operate in the reactivation of heat-... | ACCEPT | Summary: Manual review: ATPase activator activity is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0005759 mitochondrial matrix | IDA PMID:15383543 Zim17, a novel zinc finger protein essential for protein imp... | ACCEPT | Summary: Manual review: mitochondrial matrix is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0006458 'de novo' protein folding | IMP PMID:8168133 Mdj1p, a novel chaperone of the DnaJ family, is involved in ... | ACCEPT | Summary: Manual review: 'de novo' protein folding is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0006515 protein quality control for misfolded or incompletely synthesized proteins | IMP PMID:7957078 Molecular chaperones cooperate with PIM1 protease in the deg... | ACCEPT | Summary: Manual review: protein quality control for misfolded or incompletely synthesized proteins is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0009408 response to heat | IMP PMID:8603724 Role of the mitochondrial DnaJ homologue, Mdj1p, in the prev... | ACCEPT | Summary: Manual review: response to heat is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0042026 protein refolding | IMP PMID:8168133 Mdj1p, a novel chaperone of the DnaJ family, is involved in ... | ACCEPT | Summary: Manual review: protein refolding is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0042026 protein refolding | IDA PMID:9973563 Two distinct mechanisms operate in the reactivation of heat-... | ACCEPT | Summary: Manual review: protein refolding is consistent with known biology of MDJ1. Reason: Retained as supported or plausible for this gene and evidence context. |
| GO:0051082 unfolded protein binding | IMP PMID:8943361 Role of the mitochondrial DnaJ homolog Mdj1p as a chaperone ... | MODIFY | Summary: Manual review: unfolded protein binding is better represented by a more specific replacement term for MDJ1. Reason: Modified to align with current curation guidance and improve term specificity. Proposed replacements: protein folding chaperone |
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Download this section (compressed HTML)Q: Should MDJ1 receive an explicit mitochondrial genome maintenance process annotation based on nucleoid localization and mtDNA-loss phenotypes?
Q: Is direct DNA-binding/nucleoid association sufficiently represented by current GO cellular-component and process annotations?
Experiment: Test whether Mdj1 client-binding domain mutants separate mitochondrial protein-refolding activity from mtDNA maintenance in the same strain background.
Experiment: Map nucleoid-associated Mdj1 clients by proximity labeling under respiratory growth and heat-stress conditions.
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