id: Q96LL9
gene_symbol: DNAJC30
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: DNAJC30 (WBSCR18) is a mitochondrial inner-membrane DnaJ/HSP40 (J-domain) protein encoded in the 7q11.23 Williams-Beuren syndrome critical region. Imported via an N-terminal transit peptide and anchored by a single transmembrane helix, it has two intertwined roles in oxidative phosphorylation. It is an auxiliary component of the ATP synthase machinery, interacting directly with MT-ATP6 and ATP5MC2 and facilitating ATP synthesis. It also acts as a chaperone in a mitochondrial complex I (NADH:ubiquinone oxidoreductase) repair mechanism, promoting the efficient exchange/turnover of N-module subunits damaged by reactive oxygen species and thereby maintaining complex I efficiency. DNAJC30 is highly expressed in brain (pyramidal neurons). Biallelic loss-of-function variants cause autosomal-recessive Leber hereditary optic neuropathy (LHONAR1), and hemizygous loss contributes to the mitochondrial dysfunction underlying neurodevelopmental features of Williams-Beuren syndrome.
existing_annotations:
- term:
    id: GO:0005743
    label: mitochondrial inner membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Electronic (UniProt SubCell) localization to the mitochondrial inner membrane, corroborated by direct experimental evidence (PMID:30318146).
    action: ACCEPT
    reason: Correct and well-supported core localization; DNAJC30 is an inner-membrane single-pass protein.
    supported_by:
    - reference_id: file:human/DNAJC30/DNAJC30-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Mitochondrion inner membrane'
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: A large set of binary HuRI yeast two-hybrid interactions, predominantly with membrane proteins (AQP6, BEST2, EBP, MGST2, MRM1 and others) unrelated to DNAJC30's OXPHOS function. Bare protein binding is uninformative.
    action: KEEP_AS_NON_CORE
    reason: High-throughput binary interactions, many likely membrane-protein Y2H artifacts; bare protein binding is not elevated to core and the partners do not inform the ATP-synthase/complex-I function.
    supported_by:
    - reference_id: file:human/DNAJC30/DNAJC30-uniprot.txt
      supporting_text: 'Q96LL9; Q13520: AQP6; NbExp=3; IntAct=EBI-8639143, EBI-13059134'
- term:
    id: GO:0007420
    label: brain development
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: DNAJC30 is highly expressed in brain and its loss in mice diminishes neocortical pyramidal-neuron morphology and produces Williams-syndrome-like phenotypes, via mitochondrial dysfunction. This is a downstream, organ-level consequence of its mitochondrial molecular role.
    action: KEEP_AS_NON_CORE
    reason: Brain development is a pleiotropic downstream outcome of DNAJC30's mitochondrial OXPHOS function rather than its direct molecular activity; retained as non-core.
    supported_by:
    - reference_id: PMID:30318146
      supporting_text: a novel role for mitochondria in normal human brain development and WS
- term:
    id: GO:1905706
    label: regulation of mitochondrial ATP synthesis coupled proton transport
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: DNAJC30 associates with the ATP synthase complex and facilitates ATP synthesis; loss decreases the integrity of OXPHOS supercomplexes and ATP-synthase dimers. This supports a role in regulating mitochondrial ATP synthesis.
    action: ACCEPT
    reason: Supported by direct ATP-synthase interaction (MT-ATP6, ATP5MC2) and the functional role as an auxiliary component of ATP-synthase machinery.
    supported_by:
    - reference_id: PMID:30318146
      supporting_text: DNAJC30 is highly enriched in neurons and is a novel auxiliary protein of the mitochondrial ATP synthase complex
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: HTP
  original_reference_id: PMID:34800366
  qualifier: located_in
  review:
    summary: High-throughput proteomic localization to mitochondrion, consistent with and less specific than the experimentally established inner-membrane localization.
    action: ACCEPT
    reason: Correct compartment, though broader than the inner-membrane annotation.
    supported_by:
    - reference_id: file:human/DNAJC30/DNAJC30-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Mitochondrion inner membrane'
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:30318146
  qualifier: enables
  review:
    summary: Direct interaction with the ATP synthase subunits MT-ATP6 (P00846) and ATP5MC2 (Q06055), establishing DNAJC30 as an auxiliary component of ATP synthase. The bare protein binding term understates this; the biologically meaningful function is binding to the ATP synthase complex.
    action: MODIFY
    reason: Bare protein binding is uninformative; the documented partners are ATP synthase subunits, so enzyme binding better captures the molecular interaction with the ATP synthase complex.
    proposed_replacement_terms:
    - id: GO:0019899
      label: enzyme binding
    supported_by:
    - reference_id: file:human/DNAJC30/DNAJC30-uniprot.txt
      supporting_text: Interacts with MT-ATP6; interaction is direct (PubMed:30318146).
- term:
    id: GO:0005743
    label: mitochondrial inner membrane
  evidence_type: IDA
  original_reference_id: PMID:30318146
  qualifier: located_in
  review:
    summary: Direct experimental demonstration of DNAJC30 at the mitochondrial inner membrane.
    action: ACCEPT
    reason: Strongest-evidence localization; this is the core compartment of DNAJC30.
    supported_by:
    - reference_id: file:human/DNAJC30/DNAJC30-uniprot.txt
      supporting_text: Mitochondrion inner membrane
- term:
    id: GO:0007420
    label: brain development
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: involved_in
  review:
    summary: Sequence/orthology-based brain-development annotation (from mouse P59041), same downstream-phenotype caveat as the IEA brain-development term.
    action: KEEP_AS_NON_CORE
    reason: Downstream pleiotropic consequence of mitochondrial function rather than DNAJC30's direct molecular activity.
    supported_by:
    - reference_id: PMID:30318146
      supporting_text: a novel role for mitochondria in normal human brain development and WS
- term:
    id: GO:1905706
    label: regulation of mitochondrial ATP synthesis coupled proton transport
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: involved_in
  review:
    summary: Orthology-based annotation (from mouse P59041) for regulation of mitochondrial ATP synthesis, consistent with the experimental ATP-synthase association.
    action: ACCEPT
    reason: Supported by the direct ATP-synthase interaction and the role as an auxiliary ATP-synthase component.
    supported_by:
    - reference_id: file:human/DNAJC30/DNAJC30-uniprot.txt
      supporting_text: Associates with the ATP synthase complex (PubMed:30318146).
references:
- id: GO_REF:0000024
  title: Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservation of the subcellular location
  findings: []
- id: GO_REF:0000107
  title: Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara
  findings: []
- id: PMID:30318146
  title: The 7q11.23 protein DNAJC30 interacts with ATP synthase and links mitochondria to brain development.
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: "Cached publication (publications/PMID_30318146.md, full text available) title matches and establishes DNAJC30 as a mitochondrial inner-membrane protein that interacts with ATP synthase, supporting the enzyme binding core function and its role in the ATP-synthase machinery."
  findings:
  - statement: DNAJC30 is an inner-membrane mitochondrial protein that interacts directly with ATP synthase subunits (MT-ATP6, ATP5MC2) and is an auxiliary component of the ATP-synthase machinery; its loss causes mitochondrial hypofunction and Williams-syndrome-like neurodevelopmental phenotypes.
    reference_section_type: ABSTRACT
- id: PMID:32296183
  title: A reference map of the human binary protein interactome.
  findings: []
- id: PMID:33465056
  title: Impaired complex I repair causes recessive Leber's hereditary optic neuropathy.
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: "Cached publication (publications/PMID_33465056.md, full text available) title matches and establishes DNAJC30 as a chaperone required for complex I N-module subunit repair, with biallelic mutations causing recessive LHON, supporting the unfolded protein binding / chaperone core function."
  findings:
  - statement: Biallelic DNAJC30 mutations cause autosomal-recessive Leber hereditary optic neuropathy; DNAJC30 is a chaperone needed for efficient exchange of complex I N-module subunits exposed to reactive oxygen species, integral to a mitochondrial complex I repair mechanism.
    reference_section_type: ABSTRACT
- id: PMID:34800366
  title: Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context.
  findings: []
- id: file:human/DNAJC30/DNAJC30-uniprot.txt
  title: UniProt entry Q96LL9 (DJC30_HUMAN), DnaJ homolog subfamily C member 30, mitochondrial
  findings:
  - statement: Mitochondrial inner-membrane J-domain protein; associates with the ATP synthase complex and facilitates ATP synthesis; chaperone involved in turnover of complex I N-module subunits damaged by oxidative stress; causes autosomal-recessive LHON.
    reference_section_type: OTHER
core_functions:
- description: Chaperone in the mitochondrial complex I repair pathway that promotes efficient exchange/turnover of complex I (NADH:ubiquinone oxidoreductase) N-module subunits damaged by reactive oxygen species, maintaining complex I functional efficiency.
  molecular_function:
    id: GO:0051082
    label: unfolded protein binding
  locations:
  - id: GO:0005743
    label: mitochondrial inner membrane
  supported_by:
  - reference_id: PMID:33465056
    supporting_text: DNAJC30 is a chaperone protein needed for the efficient exchange of complex I subunits exposed to reactive oxygen species and integral to a mitochondrial complex I repair mechanism
- description: Auxiliary component of the mitochondrial ATP synthase machinery that interacts directly with MT-ATP6 and ATP5MC2 and facilitates ATP synthesis and OXPHOS supercomplex/ATP-synthase-dimer integrity.
  molecular_function:
    id: GO:0019899
    label: enzyme binding
  locations:
  - id: GO:0005743
    label: mitochondrial inner membrane
  supported_by:
  - reference_id: PMID:30318146
    supporting_text: DNAJC30 is highly enriched in neurons and is a novel auxiliary protein of the mitochondrial ATP synthase complex
  - reference_id: file:human/DNAJC30/DNAJC30-uniprot.txt
    supporting_text: Interacts with MT-ATP6; interaction is direct (PubMed:30318146).
proposed_new_terms: []
suggested_questions:
- question: Does DNAJC30 act mechanistically as a canonical J-domain co-chaperone (stimulating a mitochondrial HSP70 such as mortalin/HSPA9) during complex I subunit exchange, or by a non-canonical holdase/extraction mechanism?
- question: Are the ATP-synthase auxiliary role and the complex I repair role mediated by the same activity, and which is primarily disrupted by the LHONAR1 variants?
suggested_experiments:
- description: Reconstitute complex I subunit exchange in vitro or in DNAJC30-knockout cells with wild-type vs LHONAR1 variants to quantify turnover of specific N-module subunits and complex I activity.
- description: Test DNAJC30 J-domain function (HPD-motif mutagenesis, mitochondrial HSP70 ATPase-stimulation assay) to determine whether it is a bona fide co-chaperone.
- description: Cross-linking/structural analysis of DNAJC30 within the ATP synthase complex to define how it contributes to ATP-synthase dimer and supercomplex integrity.