cia30

UniProt ID: O42636
Organism: Neurospora crassa (strain ATCC 24698 / 74-OR23-1A / CBS 708.71 / DSM 1257 / FGSC 987)
Review Status: IN PROGRESS
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Gene Description

Neurospora crassa CIA30 (Complex I intermediate-associated protein 30, also known as cia35) is a mitochondrial chaperone specifically involved in the assembly of NADH:ubiquinone oxidoreductase (complex I). CIA30 is the founding member of the CIA30/NDUFAF1 family and was identified as one of two novel extra proteins (30 kDa and 84 kDa) that associate with the large membrane arm assembly intermediate of complex I but are not constituent parts of the mature complex (PMID:9769214). Disruption mutants accumulate the matrix arm and the small membrane arm assembly intermediate but cannot form the large membrane arm intermediate. Pulse-chase experiments showed that CIA30 is repeatedly involved in many assembly cycles, consistent with chaperone function (PMID:9769214). While described as a "chaperone" in the original paper, CIA30 functions specifically as a complex I assembly factor rather than as a general unfolded protein binding protein. The GO:0051082 annotation reflects binding to unassembled complex I subunits during assembly, which is a specific assembly chaperone function, not general unfolded protein binding.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005739 mitochondrion
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA annotation for mitochondrion localization. CIA30 is a mitochondrial protein, confirmed by direct experimental evidence (PMID:9769214). UniProt lists mitochondrion as the subcellular location and the protein has a mitochondrial transit peptide (residues 1-8). The IBA annotation is consistent with the IEA annotation from UniProt and the experimental evidence.
Reason: Mitochondrial localization is the primary and only documented location of CIA30, directly demonstrated in PMID:9769214. The protein has a mitochondrial transit peptide. Core localization annotation.
Supporting Evidence:
file:NEUCR/cia30/cia30-deep-research-falcon.md
In N. crassa, the cloned CIA30 protein is reported as a globular protein preceded by a typical mitochondrial import sequence of 12 amino acids, supporting mitochondrial targeting and import.
GO:0006120 mitochondrial electron transport, NADH to ubiquinone
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA annotation for mitochondrial electron transport, NADH to ubiquinone. CIA30 is required for assembly of complex I, which performs NADH:ubiquinone oxidoreduction. Without CIA30, the large membrane arm intermediate cannot be formed, and the mature complex I is not assembled (PMID:9769214). CIA30 is not a subunit of the mature complex but is essential for its assembly. The IBA annotation is appropriate as CIA30 is involved in the pathway, albeit indirectly through its assembly function.
Reason: CIA30 is essential for complex I assembly (PMID:9769214). While not a subunit of the mature complex, its loss prevents proper complex I formation and thus NADH to ubiquinone electron transport. The IBA annotation appropriately captures this involvement.
Supporting Evidence:
PMID:9769214
Mutants generated by disrupting the genes of either of the two proteins accumulate the matrix arm of complex I and the small membrane arm assembly intermediate, but are incapable of forming the large intermediate
GO:0010257 NADH dehydrogenase complex assembly
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA annotation for NADH dehydrogenase complex assembly. This is the core biological process function of CIA30. PMID:9769214 directly demonstrated that CIA30 is required for assembly of the large membrane arm intermediate of complex I, and pulse-chase experiments showed it participates in repeated assembly cycles. The IBA annotation is consistent with the NAS annotation for the more specific GO:0032981 term.
Reason: NADH dehydrogenase complex assembly is the core function of CIA30. Directly demonstrated by disruption mutants that fail to form the large membrane arm intermediate (PMID:9769214). The IBA is well supported and phylogenetically appropriate for the CIA30/NDUFAF1 family.
Supporting Evidence:
PMID:9769214
Mutants generated by disrupting the genes of either of the two proteins accumulate the matrix arm of complex I and the small membrane arm assembly intermediate, but are incapable of forming the large intermediate
PMID:9769214
Pulse-chase labelling experiments showed that the two proteins are repeatedly involved in many assembly cycles of the intermediate
file:NEUCR/cia30/cia30-deep-research-falcon.md
Neurospora complex I assembly was established to occur stepwise from intermediates. CIA30 (together with CIA84) is associated with the large membrane-arm assembly intermediate and is not found in the mature complex I holoenzyme.
GO:0051082 unfolded protein binding
IBA
GO_REF:0000033 		MARK AS OVER ANNOTATED
Summary: IBA annotation for unfolded protein binding. GO:0051082 is proposed for obsoletion (go-ontology#30962). CIA30 was described as a "novel chaperone" in the original publication (PMID:9769214), but its function is specifically as a complex I assembly factor, not as a general unfolded protein binding protein. CIA30 associates exclusively with the large membrane arm assembly intermediate of complex I and participates in repeated assembly cycles (PMID:9769214). This is a specific assembly chaperone function rather than general unfolded protein binding. The term "chaperone" as used in the original paper refers to the specific assembly assistance role, not to broad unfolded protein recognition. Per UPB project rules, specific assembly chaperones that are not general unfolded protein binding proteins should be marked as over-annotated or modified.
Reason: CIA30 is a specific complex I assembly factor, not a general unfolded protein binding protein. While described as a "chaperone" in PMID:9769214, this refers to its specific role in complex I membrane arm assembly -- it associates exclusively with the large membrane arm assembly intermediate and does not bind unfolded proteins generally. The GO:0051082 annotation overstates the generality of CIA30's binding specificity. The complex I assembly function is already captured by GO:0010257 and GO:0032981.
Supporting Evidence:
PMID:9769214
In the wild-type, the extra proteins exclusively associate with the large membrane arm assembly intermediate
PMID:9769214
These results indicate that the two proteins are novel chaperones specific for complex I membrane arm assembly
file:NEUCR/cia30/cia30-deep-research-falcon.md
The strongest organism-specific evidence indicates CIA30 is imported into mitochondria, exists in free and assembly-bound pools, and binds transiently to a large membrane-arm assembly intermediate (not the mature holoenzyme).
GO:0005739 mitochondrion
IEA
GO_REF:0000044 		ACCEPT
Summary: IEA annotation for mitochondrion from UniProt subcellular location mapping. Consistent with the IBA annotation for the same term and the direct experimental evidence from PMID:9769214. UniProt lists mitochondrion as the subcellular location.
Reason: Consistent with IBA annotation and direct experimental evidence. Mitochondrion is the primary and only documented location of CIA30.
GO:0032981 mitochondrial respiratory chain complex I assembly
NAS
PMID:9769214
Involvement of two novel chaperones in the assembly of mitoc... 		ACCEPT
Summary: NAS annotation for mitochondrial respiratory chain complex I assembly from PMID:9769214. This is the core biological process function of CIA30. The original paper titled "Involvement of two novel chaperones in the assembly of mitochondrial NADH:Ubiquinone oxidoreductase (complex I)" directly describes the role of CIA30 in complex I assembly. The NAS evidence code is appropriate as the paper provides direct experimental evidence for complex I assembly involvement. This is a more specific child of GO:0010257.
Reason: Complex I assembly is the core function of CIA30. PMID:9769214 directly demonstrated this through disruption mutants, pulse-chase experiments, and co-purification with assembly intermediates. This more specific term (child of GO:0010257) appropriately captures the respiratory chain complex I assembly function.
Supporting Evidence:
PMID:9769214
These results indicate that the two proteins are novel chaperones specific for complex I membrane arm assembly
GO:0051082 unfolded protein binding
IDA
PMID:9769214
Involvement of two novel chaperones in the assembly of mitoc... 		MARK AS OVER ANNOTATED
Summary: IDA annotation for unfolded protein binding from PMID:9769214. GO:0051082 is proposed for obsoletion (go-ontology#30962). The original paper demonstrated that CIA30 associates with the large membrane arm assembly intermediate of complex I and is involved in repeated assembly cycles (PMID:9769214: "the extra proteins exclusively associate with the large membrane arm assembly intermediate" and "Pulse-chase labelling experiments showed that the two proteins are repeatedly involved in many assembly cycles"). The authors called CIA30 a "chaperone" but specified it was "specific for complex I membrane arm assembly." This is a specific assembly factor function, not general unfolded protein binding. The protein does not bind unfolded proteins broadly -- it binds specifically to complex I assembly intermediates. The IDA evidence demonstrates complex I assembly intermediate binding, not general unfolded protein binding.
Reason: The IDA evidence from PMID:9769214 demonstrates that CIA30 binds specifically to complex I assembly intermediates, not to unfolded proteins generally. The original paper explicitly states the proteins are "chaperones specific for complex I membrane arm assembly." GO:0051082 overstates the generality of the binding. The complex I assembly function is better captured by GO:0032981 and GO:0010257. While CIA30 may indeed interact with unfolded or partially assembled complex I subunits, calling this "unfolded protein binding" conflates a specific assembly factor role with general chaperone function.
Supporting Evidence:
PMID:9769214
In the wild-type, the extra proteins exclusively associate with the large membrane arm assembly intermediate
PMID:9769214
Pulse-chase labelling experiments showed that the two proteins are repeatedly involved in many assembly cycles of the intermediate
PMID:9769214
These results indicate that the two proteins are novel chaperones specific for complex I membrane arm assembly
GO:0044183 protein folding chaperone
NAS
PMID:9769214
Involvement of two novel chaperones in the assembly of mitoc... 		NEW
Summary: New molecular-function annotation to capture CIA30's chaperone-like role in mitochondrial complex I assembly. The evidence supports a specific assembly chaperone activity for complex I membrane-arm intermediates, not broad unfolded-protein binding.
Reason: GO:0044183 better reflects the core molecular function already summarized for CIA30 than GO:0051082. CIA30 is transiently associated with complex I assembly intermediates, is not a mature complex I subunit, and was described as a chaperone specific for complex I membrane arm assembly. This NEW annotation should be interpreted narrowly as assembly-chaperone activity for mitochondrial respiratory chain complex I biogenesis.
Supporting Evidence:
PMID:9769214
These results indicate that the two proteins are novel chaperones specific for complex I membrane arm assembly
file:NEUCR/cia30/cia30-deep-research-falcon.md
CIA30 is a transient complex I assembly factor/chaperone, not a mature holoenzyme subunit. In N. crassa it associates with the large membrane-arm assembly intermediate and is released during assembly progression.

Core Functions

CIA30 functions as a specific assembly chaperone for complex I membrane arm formation. It associates with the large membrane arm assembly intermediate and participates in repeated assembly cycles (PMID:9769214). The "chaperone" designation reflects its role in assisting complex I subunit assembly rather than general unfolded protein binding. While GO:0044183 is used as the closest available MF term, CIA30's function is more specifically as an assembly factor than as a general protein folding chaperone.

Molecular Function:
protein folding chaperone
Directly Involved In:
mitochondrial respiratory chain complex I assembly mitochondrial electron transport, NADH to ubiquinone
Cellular Locations:
mitochondrion
Supporting Evidence:
  • PMID:9769214
    These results indicate that the two proteins are novel chaperones specific for complex I membrane arm assembly
  • PMID:9769214
    Pulse-chase labelling experiments showed that the two proteins are repeatedly involved in many assembly cycles of the intermediate

References

GO_REF:0000033
Annotation inferences using phylogenetic trees
GO_REF:0000044
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
PMID:9769214
Involvement of two novel chaperones in the assembly of mitochondrial NADH:Ubiquinone oxidoreductase (complex I).
file:NEUCR/cia30/cia30-deep-research-falcon.md
Deep research report on cia30 (Falcon/Edison Scientific Literature)
  • cia30 is the Neurospora crassa complex I assembly factor (CIA30/NDUFAF1 ortholog) that chaperones the assembly of the mitochondrial NADH:ubiquinone oxidoreductase (Complex I) by stabilizing early subassembly intermediates.

Deep Research

Falcon

(cia30-deep-research-falcon.md)
Research Report: Functional Annotation of *Neurospora crassa* **cia30** (UniProt O42636; NCU01975) Falcon Edison Scientific Literature 18 citations 2 artifacts 2026-05-23T00:44:47.153208
Edison artifact artifact-00 (text/markdown)
## Context ID: pqac-00000020 Figure 1A shows the early PP module intermediate, which is the core complex of the NDUFAF1-dependent assembly pathway. This complex (image/png)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

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Research Report: Functional Annotation of Neurospora crassa cia30 (UniProt O42636; NCU01975)

Executive summary

The Neurospora crassa gene cia30 (UniProt O42636; synonyms cia35; ORF NCU01975) encodes Complex I intermediate-associated protein 30 kDa (CIA30), a mitochondrial respiratory complex I assembly factor (the fungal ortholog of mammalian NDUFAF1). The strongest organism-specific evidence indicates CIA30 is imported into mitochondria, exists in free and assembly-bound pools, and binds transiently to a large membrane-arm assembly intermediate (not the mature holoenzyme). Genetic/biochemical analyses support a specific role in complex I biogenesis rather than a pleiotropic effect on other OXPHOS complexes. Recent (2023–2024) structural work in genetically tractable fungi and mechanistic work on the conserved MCIA pathway in mammals now clarify how CIA30/NDUFAF1 stabilizes membrane-arm assembly intermediates—particularly by sequestering the ND3 TMH1–2 loop (protecting a conserved cysteine) and coordinating PP-module maturation—providing updated, mechanistically grounded functional annotation.

1) Key concepts, definitions, and current understanding

1.1 Respiratory complex I and “assembly factors”

Mitochondrial respiratory complex I (NADH:ubiquinone oxidoreductase) is a ~1 MDa enzyme in many eukaryotes that couples electron transfer from NADH to ubiquinone with proton pumping across the inner mitochondrial membrane. Modern module terminology partitions complex I into the N module (NADH oxidation), Q module (ubiquinone reduction), and proximal and distal proton-pumping modules (PP and PD). (schiller2022insightsintocomplex pages 1-2)

“Assembly factors” are proteins not present in the mature holoenzyme but required for stepwise construction of complex I through transient intermediates; defects in these factors can stall assembly and lead to accumulation of subcomplexes. CIA30/NDUFAF1 is a canonical example. (schulte2001biogenesisofrespiratory pages 2-4, dunning2007humancia30is pages 8-9)

1.2 CIA30/NDUFAF1 family identity (verification against the user’s target)

High-authority sources explicitly state that NDUFAF1 was first described as CIA30 in the filamentous fungus Neurospora crassa, and they connect CIA30 to complex I assembly intermediates. This matches the UniProt O42636 description (“Complex I intermediate-associated protein 30, mitochondrial; precursor”) and the CIA30/NDUFAF1-family assignment. (schiller2022insightsintocomplex pages 1-2, dunning2007humancia30is pages 1-2)

2) Organism-specific functional evidence for N. crassa CIA30 (cia30/NCU01975)

2.1 Subcellular localization: mitochondrial import

In N. crassa, the cloned CIA30 protein is reported as a globular protein preceded by a typical mitochondrial import sequence of 12 amino acids, supporting mitochondrial targeting and import. (schulte2001biogenesisofrespiratory pages 2-4)

2.2 Primary function: complex I assembly factor (not a catalytic subunit)

Neurospora complex I assembly was established to occur stepwise from intermediates. CIA30 (together with CIA84) is associated with the large membrane-arm assembly intermediate and is not found in the mature complex I holoenzyme, consistent with an assembly factor/chaperone function. (schulte2001biogenesisofrespiratory pages 2-4, dunning2007humancia30is pages 8-9)

2.3 Pathway placement: membrane-arm intermediate association and assembly-state dependence

In N. crassa, the large membrane-arm intermediate contains five mitochondrially encoded subunits and six nuclear-encoded subunits, and it is specifically the intermediate to which CIA30 associates. (schulte2001biogenesisofrespiratory pages 2-4)

CIA proteins (CIA30/CIA84) exist in two pools: bound to the assembly intermediate and free/unbound. In wild type, roughly equal amounts are present in each pool; when small membrane-arm assembly is blocked, the large intermediate accumulates and CIA proteins shift predominantly from free to bound. Conversely, mutants unable to form a stable large intermediate show CIA proteins exclusively free. This supports a model in which CIA30 cycles between a reservoir pool and an intermediate-bound functional pool during assembly. (schulte2001biogenesisofrespiratory pages 2-4)

2.4 Complex I specificity of cia phenotypes

Schulte (2001) reports that characterization of cia mutants indicates complex I is the only respiratory complex affected, and no other target for CIA proteins was identified in those analyses. This supports annotating cia30 as a complex-I-specific biogenesis factor rather than a general mitochondrial maintenance protein. (schulte2001biogenesisofrespiratory pages 2-4)

2.5 Assembly intermediates: reported molecular sizes (350/200 kDa)

Neurospora genetic disruption of a complex I subunit (21.3 kDa) produced assembly defects with accumulation of ~350 kDa and ~200 kDa membrane intermediates; the ~350 kDa intermediate contained multiple mtDNA-encoded and at least six nuclear-encoded subunits and was associated with CIA30 and CIA84. CIA30 and CIA84 appeared to bind this intermediate independently and not to fully assembled complex I. (dunning2007humancia30is pages 8-9)

Important limitation: The accessible sources here provide strong evidence for intermediate association and assembly specificity, but they do not provide detailed organismal phenotypes (growth, development, stress) for a clean cia30 null mutant in N. crassa; such phenotypes are mentioned generally as “severe disruption of assembly” without detailed quantitative organism-level readouts in the excerpts obtained. (janssen2002cia30complexi pages 1-2)

3) Mechanistic and structural interpretation (updated by 2022–2024 research)

Although much of the high-resolution mechanistic detail comes from the yeast model Yarrowia lipolytica and mammalian systems, these are directly relevant because CIA30 is orthologous to NDUFAF1 and participates in a conserved PP/membrane-arm assembly pathway.

3.1 PP-module “seed” complex and role of CIA30/NDUFAF1

Cryo-EM of NDUFAF1-associated intermediates shows that subunits ND2 and NDUFC2, together with NDUFAF1 (CIA30) and fungal CIA84, form a nucleation (“seed”) complex for the NDUFAF1-dependent assembly pathway of the PP module. NDUFAF1 also “locks” the ND3 subunit in an assembly-competent conformation during PP-module maturation. (schiller2022insightsintocomplex pages 1-2)

3.2 2023–2024: high-resolution structural details of NDUFAF1-associated intermediates

A 2024 cryo-EM-focused review summarizes that NDUFAF1-associated complexes of ~170 kDa (early PP intermediate) and ~280 kDa (late PP intermediate) were obtained at 3.2 Å resolution. Mechanistically, NDUFAF1 binds the ND3 TMH1–2 loop in a cleft, sequestering a conserved cysteine; this both enforces an assembly-specific ND3 topology and plausibly protects a chemically sensitive region important for later complex I function. (laube2024usingcryoemto pages 3-4)

Unexpectedly, tafazzin (a cardiolipin-remodeling transacylase) was found as an integral component of the early NDUFAF1-dependent PP “seed” complex (in Y. lipolytica), linking lipid remodeling to assembly of the membrane/proton-pumping arm. (schiller2022insightsintocomplex pages 1-2)

3.4 2023: MCIA complex mechanism (conserved pathway context for NDUFAF1)

In mammals, NDUFAF1 participates in the MCIA (mitochondrial complex I intermediate assembly) pathway. A 2023 Nature Communications study resolved how MCIA subunits ECSIT and ACAD9 form a core complex: ECSIT binding induces conformational change in ACAD9’s FAD-binding loop, triggers FAD release, and switches ACAD9 from a fatty-acid β-oxidation enzyme to a complex I assembly factor. The study identified a critical ECSIT Glu323–ACAD9 Lys228 salt bridge (E323A abolishes binding) and showed a minimal 15-residue ECSIT peptide can be sufficient for complex formation. While these data are not Neurospora-specific, they provide authoritative mechanistic context for the conserved NDUFAF1-containing PP/membrane-arm assembly pathway. (mcgregor2023theassemblyof pages 1-2, laube2024usingcryoemto pages 7-9)

4) Current applications and real-world implementations

4.1 Functional annotation and mitochondrial biology modeling

Neurospora crassa remains a key aerobic fungal model for dissecting complex I assembly via genetics and biochemistry, because assembly intermediates can be tracked and mutants constructed. CIA30 is central to this work as one of the earliest identified complex-I-specific assembly factors. (schulte2001biogenesisofrespiratory pages 2-4, dunning2007humancia30is pages 1-2)

4.2 Translational relevance: human disease and diagnostic genetics (orthology-based)

The discovery of N. crassa CIA30 motivated screening of the human ortholog (NDUFAF1) as a candidate for complex I deficiency. This is an important “real-world” use of CIA30-family functional annotation: identifying mitochondrial disease genes and interpreting complexome/BN-PAGE patterns in patient samples. (janssen2002cia30complexi pages 1-2, dunning2007humancia30is pages 8-9)

5) Expert opinion and synthesis (authoritative interpretation)

The prevailing expert interpretation is that CIA30/NDUFAF1-family proteins function as assembly chaperones that:
1) associate transiently with membrane-arm/PP intermediates rather than the mature enzyme, and
2) stabilize or protect key membrane subunits (notably ND3) in assembly-specific conformations until later modules join.

This interpretation is consistent across organism-specific Neurospora evidence (intermediate association, bound/free pools, complex I specificity) and modern structural data (ND3 loop sequestration; early PP seed complexes). (schulte2001biogenesisofrespiratory pages 2-4, laube2024usingcryoemto pages 3-4, schiller2022insightsintocomplex pages 1-2)

6) Relevant statistics and quantitative findings from recent studies

  • Complex I modular definitions and size: Complex I is described as a ~1 MDa membrane complex in mitochondria. (schiller2022insightsintocomplex pages 1-2, mcgregor2023theassemblyof pages 1-2)
  • Quantitative assembly dependence: In Y. lipolytica, deletion of NDUFAF1 reduced complex I content (NADH:hexaammineruthenium assay) to ~14%, and ubiquinone reductase activity was below detection, indicating failure to assemble functional complex I. (schiller2022insightsintocomplex pages 1-2)
  • Structural intermediate sizes/resolution: NDUFAF1-associated early/late PP intermediates were reported at ~170 kDa and ~280 kDa and mapped at 3.2 Å. (laube2024usingcryoemto pages 3-4)
  • Neurospora intermediate sizes: Assembly defects in N. crassa can produce membrane intermediates at ~350 kDa and ~200 kDa, with CIA30/CIA84 bound to the ~350 kDa intermediate. (dunning2007humancia30is pages 8-9)
  • Molecular interaction detail (MCIA core): A minimal 15-residue ECSIT peptide can mediate binding to ACAD9; an ECSIT Glu323–ACAD9 Lys228 salt bridge is critical (mutation E323A abolishes binding). (mcgregor2023theassemblyof pages 1-2)

Visual evidence from primary structural study

The following cropped figure panel shows the NDUFAF1/CIA30-associated early and late PP-module assembly intermediates (including ND2/NDUFC2 with NDUFAF1/CIA84 and tafazzin in the early intermediate, and the late intermediate containing ND3 held in an assembly-competent conformation).

(schiller2022insightsintocomplex media a5675587)

Evidence table (traceable claims)

Claim/annotation field Organism/system Key evidence (1-2 sentences) Publication (first author, year, journal) URL Citation ID
Verified identity / family assignment Neurospora crassa; conserved fungal/animal orthology CIA30 was first described in N. crassa as a complex I intermediate-associated protein; later work identifies human NDUFAF1 as its ortholog, supporting annotation of UniProt O42636 as the fungal CIA30/NDUFAF1-family assembly factor rather than a catalytic complex I subunit. Schiller, 2022, Science Advances https://doi.org/10.1126/sciadv.add3855 (schiller2022insightsintocomplex pages 1-2)
Primary molecular function N. crassa CIA30 is a transient complex I assembly factor/chaperone, not a mature holoenzyme subunit. In N. crassa it associates with the large membrane-arm assembly intermediate and is released during assembly progression. Schulte, 2001, Journal of Bioenergetics and Biomembranes https://doi.org/10.1023/a:1010730919074 (schulte2001biogenesisofrespiratory pages 2-4)
Biological process N. crassa Complex I assembly proceeds modularly, with peripheral and membrane arms formed separately; CIA30 participates specifically in membrane-arm biogenesis by associating with the large membrane-arm intermediate. Schulte, 2001, Journal of Bioenergetics and Biomembranes https://doi.org/10.1023/a:1010730919074 (schulte2001biogenesisofrespiratory pages 2-4)
Subcellular localization N. crassa CIA30 has an N-terminal mitochondrial import sequence of 12 amino acids, supporting mitochondrial localization consistent with its role in respiratory complex I biogenesis. Schulte, 2001, Journal of Bioenergetics and Biomembranes https://doi.org/10.1023/a:1010730919074 (schulte2001biogenesisofrespiratory pages 2-4)
Sub-mitochondrial localization / topology inference Human ortholog; relevant conserved inference for fungal CIA30 Human CIA30/NDUFAF1 is imported into the mitochondrial matrix and associates with inner-membrane assembly intermediates. This strongly supports annotation of fungal CIA30 as a matrix-side assembly factor acting on the inner membrane arm during assembly. Dunning, 2007, The EMBO Journal https://doi.org/10.1038/sj.emboj.7601748 (dunning2007humancia30is pages 8-9, dunning2007humancia30is pages 1-2)
Complex/intermediate association N. crassa The large membrane-arm intermediate contains five mitochondrially encoded and six nuclear-encoded complex I subunits plus CIA30 and CIA84; CIA30 is absent from mature complex I. Schulte, 2001, Journal of Bioenergetics and Biomembranes https://doi.org/10.1023/a:1010730919074 (schulte2001biogenesisofrespiratory pages 2-4)
Intermediate size / composition N. crassa Disruption of a 21.3 kDa complex I subunit caused accumulation of ~350 kDa and ~200 kDa membrane intermediates; the ~350 kDa species contains multiple mtDNA-encoded subunits, at least six nuclear-encoded subunits, and CIA30/CIA84. Dunning, 2007, The EMBO Journal https://doi.org/10.1038/sj.emboj.7601748 (dunning2007humancia30is pages 8-9)
Bound versus free assembly-factor pools N. crassa In wild type, CIA proteins exist in roughly equal bound and free pools. Blocking small membrane-arm assembly shifts CIA proteins toward the bound pool, whereas failure to form a stable large intermediate leaves CIA proteins exclusively free. Schulte, 2001, Journal of Bioenergetics and Biomembranes https://doi.org/10.1023/a:1010730919074 (schulte2001biogenesisofrespiratory pages 2-4)
Specificity of effect N. crassa Characterization of cia mutants indicates that complex I is the only respiratory complex detectably affected; no other respiratory target was identified in the cited study. Schulte, 2001, Journal of Bioenergetics and Biomembranes https://doi.org/10.1023/a:1010730919074 (schulte2001biogenesisofrespiratory pages 2-4)
Role in mature enzyme vs assembly N. crassa CIA30 and CIA84 bind independently to the ~350 kDa assembly intermediate but do not interact with fully assembled complex I, supporting a chaperone/assembly-factor role rather than a structural role in the final enzyme. Dunning, 2007, The EMBO Journal https://doi.org/10.1038/sj.emboj.7601748 (dunning2007humancia30is pages 8-9)
Gene disruption / phenotype when disrupted N. crassa and family-level inference Deletion/disruption of CIA genes in N. crassa severely disrupts complex I assembly, motivating their use as candidate assembly-factor genes in other organisms. This supports annotation of cia30 as essential for efficient complex I biogenesis. Janssen, 2002, Human Genetics https://doi.org/10.1007/s00439-001-0673-3 (janssen2002cia30complexi pages 1-2)
Conserved assembly pathway role Yeast (Yarrowia lipolytica) Cryo-EM shows NDUFAF1-dependent assembly starts from an early PP-module “seed” containing ND2, NDUFC2, NDUFAF1 and fungal CIA84; a later PP intermediate contains all 12 PP-module subunits. This refines functional annotation of fungal CIA30 as an early PP/membrane-arm assembly factor. Schiller, 2022, Science Advances https://doi.org/10.1126/sciadv.add3855 (schiller2022insightsintocomplex pages 1-2, schiller2022insightsintocomplex media a5675587)
Mechanism: conformational control Yeast (Yarrowia lipolytica) NDUFAF1/CIA30 locks the central ND3 subunit in an assembly-competent conformation and binds the ND3 TMH1–2 loop, preventing premature rearrangements during PP-module maturation. Schiller, 2022, Science Advances https://doi.org/10.1126/sciadv.add3855 (schiller2022insightsintocomplex pages 1-2)
Mechanism: protective binding of ND3 loop Yeast (Yarrowia lipolytica) At 3.2 Å resolution, NDUFAF1 is seen to sequester the ND3 TMH1–2 loop and shield its conserved cysteine in a binding cleft, implying a protective role during assembly before later module joining. Laube, 2024, Acta Crystallographica D https://doi.org/10.1107/S205979832400086X (laube2024usingcryoemto pages 3-4, laube2024usingcryoemto pages 4-7)
Quantitative structural data Yeast (Yarrowia lipolytica) NDUFAF1-associated early and late PP intermediates were resolved as ~170 kDa and ~280 kDa complexes at 3.2 Å resolution, providing direct structural support for transient assembly-factor association. Laube, 2024, Acta Crystallographica D https://doi.org/10.1107/S205979832400086X (laube2024usingcryoemto pages 3-4)
Quantitative disruption phenotype Yeast (Yarrowia lipolytica) Deletion of NDUFAF1 reduced complex I content to ~14% of control and abolished detectable ubiquinone reductase activity, demonstrating that CIA30-family proteins are essential assembly factors rather than accessory stabilizers. Schiller, 2022, Science Advances https://doi.org/10.1126/sciadv.add3855 (schiller2022insightsintocomplex pages 1-2)
Conserved partner proteins / pathway context Mammalian MCIA complex NDUFAF1 is part of the mitochondrial complex I intermediate assembly (MCIA) complex with ECSIT and ACAD9, with additional peripheral membrane components; this places CIA30-family proteins in a conserved assembly network for the membrane/PP arm. McGregor, 2023, Nature Communications https://doi.org/10.1038/s41467-023-43865-0 (mcgregor2023theassemblyof pages 1-2)
Conserved mechanistic partner insight Mammalian MCIA complex ECSIT binding remodels ACAD9 and triggers FAD release, converting ACAD9 from a fatty-acid oxidation enzyme into a complex I assembly factor. Although CIA30 itself is not catalytic, this explains the mechanistic context of the NDUFAF1-containing MCIA pathway. McGregor, 2023, Nature Communications https://doi.org/10.1038/s41467-023-43865-0 (mcgregor2023theassemblyof pages 1-2)
Interaction landscape in vertebrates Human CIA30/NDUFAF1 associates with newly translated mtDNA-encoded ND1, ND2 and ND3 and with many nuclear-encoded complex I subunits; it co-migrates with B460 and B830 kDa assembly intermediates but not with late-assembling NDUFS5. Dunning, 2007, The EMBO Journal https://doi.org/10.1038/sj.emboj.7601748 (dunning2007humancia30is pages 8-9)
Quantitative intermediate sizes in vertebrates Human CIA30-containing complexes were observed at ~440–500 and 600–700 kDa in one study, with related reports placing them at 500–850 kDa; these detergent-sensitive assemblies are consistent with transient association with assembly intermediates rather than the mature holoenzyme. Dunning, 2007, The EMBO Journal https://doi.org/10.1038/sj.emboj.7601748 (dunning2007humancia30is pages 8-9)
Pathway terminology / module definitions Eukaryotic complex I, general Authoritative structural work defines the N module for NADH oxidation, the Q module for ubiquinone reduction, and the proximal/distal P modules (PP/PD) for proton pumping. CIA30/NDUFAF1 acts in PP-module assembly, which maps well onto earlier “membrane-arm intermediate” terminology from N. crassa. Schiller, 2022, Science Advances https://doi.org/10.1126/sciadv.add3855 (schiller2022insightsintocomplex pages 1-2)
Link to membrane lipid remodeling Yeast (Yarrowia lipolytica) Tafazzin, the cardiolipin-remodeling enzyme, was unexpectedly found as an integral component of the early NDUFAF1/CIA30-containing PP seed complex, linking complex I assembly to cardiolipin remodeling. Schiller, 2022, Science Advances https://doi.org/10.1126/sciadv.add3855 (schiller2022insightsintocomplex pages 1-2, schiller2022insightsintocomplex media a5675587)

Table: This table summarizes organism-specific evidence for Neurospora crassa CIA30 and conserved mechanistic insights from orthologous NDUFAF1/CIA30 studies. It is useful for functional annotation because it separates direct Neurospora findings from higher-confidence family-level inferences about localization, assembly intermediates, mechanism, and disruption phenotypes.

Practical functional annotation recommendation for cia30 (O42636)

Based on the evidence above, the most defensible annotation for N. crassa CIA30 is:
* Molecular function: mitochondrial complex I assembly factor (chaperone-like), binds transient membrane-arm/PP intermediates; not a complex I catalytic subunit. (schulte2001biogenesisofrespiratory pages 2-4, dunning2007humancia30is pages 8-9)
* Biological process: assembly/biogenesis of mitochondrial respiratory chain complex I (particularly membrane arm / PP module). (schulte2001biogenesisofrespiratory pages 2-4, schiller2022insightsintocomplex pages 1-2)
* Cellular component: mitochondrion (import sequence), likely matrix-side association with inner membrane assembly intermediates. (schulte2001biogenesisofrespiratory pages 2-4, dunning2007humancia30is pages 8-9)
* Pathway context: complex I assembly pathway; functionally connected (by orthology) to NDUFAF1-dependent PP assembly and, in metazoans, MCIA network (NDUFAF1/ECSIT/ACAD9). (schiller2022insightsintocomplex pages 1-2, mcgregor2023theassemblyof pages 1-2)

References (selected; with publication dates and URLs)

  • Schulte U. Biogenesis of respiratory complex I. Journal of Bioenergetics and Biomembranes. June 2001. https://doi.org/10.1023/a:1010730919074 (schulte2001biogenesisofrespiratory pages 2-4)
  • Janssen R, et al. CIA30 complex I assembly factor: a candidate for human complex I deficiency? Human Genetics. Published online 1 Feb 2002 (Accepted 9 Dec 2001). https://doi.org/10.1007/s00439-001-0673-3 (janssen2002cia30complexi pages 1-2)
  • Dunning CJR, et al. Human CIA30 is involved in the early assembly of mitochondrial complex I and mutations in its gene cause disease. The EMBO Journal. July 2007. https://doi.org/10.1038/sj.emboj.7601748 (dunning2007humancia30is pages 8-9)
  • Schiller J, et al. Insights into complex I assembly: Function of NDUFAF1 and a link with cardiolipin remodeling. Science Advances. 16 Nov 2022. https://doi.org/10.1126/sciadv.add3855 (schiller2022insightsintocomplex pages 1-2)
  • McGregor L, et al. The assembly of the Mitochondrial Complex I Assembly complex uncovers a redox pathway coordination. Nature Communications. Accepted 21 Nov 2023 (Received 13 Mar 2023). https://doi.org/10.1038/s41467-023-43865-0 (mcgregor2023theassemblyof pages 1-2)
  • Laube E, et al. Using cryo-EM to understand the assembly pathway of respiratory complex I. Acta Crystallographica Section D: Structural Biology. Feb 2024. https://doi.org/10.1107/S205979832400086X (laube2024usingcryoemto pages 3-4)

References

  1. (schiller2022insightsintocomplex pages 1-2): Jonathan Schiller, Eike Laube, Ilka Wittig, Werner Kühlbrandt, Janet Vonck, and Volker Zickermann. Insights into complex i assembly: function of ndufaf1 and a link with cardiolipin remodeling. Science Advances, Nov 2022. URL: https://doi.org/10.1126/sciadv.add3855, doi:10.1126/sciadv.add3855. This article has 28 citations and is from a highest quality peer-reviewed journal.

  2. (schulte2001biogenesisofrespiratory pages 2-4): Ulrich Schulte. Biogenesis of respiratory complex i. Journal of Bioenergetics and Biomembranes, 33:205-212, Jun 2001. URL: https://doi.org/10.1023/a:1010730919074, doi:10.1023/a:1010730919074. This article has 82 citations and is from a peer-reviewed journal.

  3. (dunning2007humancia30is pages 8-9): Christopher J.R. Dunning, Matthew McKenzie, C. Sugiana, M. Lazarou, John Silke, A. Connelly, Janice M. Fletcher, D. Kirby, David R. Thorburn, and Michael T. Ryan. Human cia30 is involved in the early assembly of mitochondrial complex i and mutations in its gene cause disease. The EMBO Journal, 26:3227-3237, Jul 2007. URL: https://doi.org/10.1038/sj.emboj.7601748, doi:10.1038/sj.emboj.7601748. This article has 246 citations.

  4. (dunning2007humancia30is pages 1-2): Christopher J.R. Dunning, Matthew McKenzie, C. Sugiana, M. Lazarou, John Silke, A. Connelly, Janice M. Fletcher, D. Kirby, David R. Thorburn, and Michael T. Ryan. Human cia30 is involved in the early assembly of mitochondrial complex i and mutations in its gene cause disease. The EMBO Journal, 26:3227-3237, Jul 2007. URL: https://doi.org/10.1038/sj.emboj.7601748, doi:10.1038/sj.emboj.7601748. This article has 246 citations.

  5. (janssen2002cia30complexi pages 1-2): Rolf Janssen, Jan Smeitink, Roel Smeets, and Lambert van den Heuvel. Cia30 complex i assembly factor: a candidate for human complex i deficiency? Human Genetics, 110:264-270, Feb 2002. URL: https://doi.org/10.1007/s00439-001-0673-3, doi:10.1007/s00439-001-0673-3. This article has 94 citations and is from a peer-reviewed journal.

  6. (laube2024usingcryoemto pages 3-4): Eike Laube, Jonathan Schiller, Volker Zickermann, and Janet Vonck. Using cryo-em to understand the assembly pathway of respiratory complex i. Acta Crystallographica. Section D, Structural Biology, 80:159-173, Feb 2024. URL: https://doi.org/10.1107/s205979832400086x, doi:10.1107/s205979832400086x. This article has 8 citations.

  7. (mcgregor2023theassemblyof pages 1-2): Lindsay McGregor, Samira Acajjaoui, Ambroise Desfosses, Melissa Saïdi, Maria Bacia-Verloop, Jennifer J. Schwarz, Pauline Juyoux, Jill von Velsen, Matthew W. Bowler, Andrew A. McCarthy, Eaazhisai Kandiah, Irina Gutsche, and Montserrat Soler-Lopez. The assembly of the mitochondrial complex i assembly complex uncovers a redox pathway coordination. Nature Communications, Dec 2023. URL: https://doi.org/10.1038/s41467-023-43865-0, doi:10.1038/s41467-023-43865-0. This article has 31 citations and is from a highest quality peer-reviewed journal.

  8. (laube2024usingcryoemto pages 7-9): Eike Laube, Jonathan Schiller, Volker Zickermann, and Janet Vonck. Using cryo-em to understand the assembly pathway of respiratory complex i. Acta Crystallographica. Section D, Structural Biology, 80:159-173, Feb 2024. URL: https://doi.org/10.1107/s205979832400086x, doi:10.1107/s205979832400086x. This article has 8 citations.

  9. (schiller2022insightsintocomplex media a5675587): Jonathan Schiller, Eike Laube, Ilka Wittig, Werner Kühlbrandt, Janet Vonck, and Volker Zickermann. Insights into complex i assembly: function of ndufaf1 and a link with cardiolipin remodeling. Science Advances, Nov 2022. URL: https://doi.org/10.1126/sciadv.add3855, doi:10.1126/sciadv.add3855. This article has 28 citations and is from a highest quality peer-reviewed journal.

  10. (laube2024usingcryoemto pages 4-7): Eike Laube, Jonathan Schiller, Volker Zickermann, and Janet Vonck. Using cryo-em to understand the assembly pathway of respiratory complex i. Acta Crystallographica. Section D, Structural Biology, 80:159-173, Feb 2024. URL: https://doi.org/10.1107/s205979832400086x, doi:10.1107/s205979832400086x. This article has 8 citations.

Artifacts

Citations

  1. schiller2022insightsintocomplex pages 1-2
  2. schulte2001biogenesisofrespiratory pages 2-4
  3. laube2024usingcryoemto pages 3-4
  4. mcgregor2023theassemblyof pages 1-2
  5. laube2024usingcryoemto pages 7-9
  6. laube2024usingcryoemto pages 4-7
  7. https://doi.org/10.1126/sciadv.add3855
  8. https://doi.org/10.1023/a:1010730919074
  9. https://doi.org/10.1038/sj.emboj.7601748
  10. https://doi.org/10.1007/s00439-001-0673-3
  11. https://doi.org/10.1107/S205979832400086X
  12. https://doi.org/10.1038/s41467-023-43865-0
  13. https://doi.org/10.1126/sciadv.add3855,
  14. https://doi.org/10.1023/a:1010730919074,
  15. https://doi.org/10.1038/sj.emboj.7601748,
  16. https://doi.org/10.1007/s00439-001-0673-3,
  17. https://doi.org/10.1107/s205979832400086x,
  18. https://doi.org/10.1038/s41467-023-43865-0,

📄 View Raw YAML

 
id: O42636
gene_symbol: cia30
product_type: PROTEIN
status: IN_PROGRESS
taxon:
  id: NCBITaxon:367110
  label: Neurospora crassa (strain ATCC 24698 / 74-OR23-1A / CBS 708.71 / DSM 1257
    / FGSC 987)
description: >-
  Neurospora crassa CIA30 (Complex I intermediate-associated protein 30, also known as
  cia35) is a mitochondrial chaperone specifically involved in the assembly of NADH:ubiquinone
  oxidoreductase (complex I). CIA30 is the founding member of the CIA30/NDUFAF1 family and
  was identified as one of two novel extra proteins (30 kDa and 84 kDa) that associate with
  the large membrane arm assembly intermediate of complex I but are not constituent parts
  of the mature complex (PMID:9769214). Disruption mutants accumulate the matrix arm and the
  small membrane arm assembly intermediate but cannot form the large membrane arm intermediate.
  Pulse-chase experiments showed that CIA30 is repeatedly involved in many assembly cycles,
  consistent with chaperone function (PMID:9769214). While described as a "chaperone" in the
  original paper, CIA30 functions specifically as a complex I assembly factor rather than as
  a general unfolded protein binding protein. The GO:0051082 annotation reflects binding to
  unassembled complex I subunits during assembly, which is a specific assembly chaperone
  function, not general unfolded protein binding.
existing_annotations:
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for mitochondrion localization. CIA30 is a mitochondrial protein,
      confirmed by direct experimental evidence (PMID:9769214). UniProt lists mitochondrion
      as the subcellular location and the protein has a mitochondrial transit peptide
      (residues 1-8). The IBA annotation is consistent with the IEA annotation from
      UniProt and the experimental evidence.
    action: ACCEPT
    reason: >-
      Mitochondrial localization is the primary and only documented location of CIA30,
      directly demonstrated in PMID:9769214. The protein has a mitochondrial transit
      peptide. Core localization annotation.
    additional_reference_ids:
      - file:NEUCR/cia30/cia30-deep-research-falcon.md
    supported_by:
      - reference_id: file:NEUCR/cia30/cia30-deep-research-falcon.md
        supporting_text: >-
          In N. crassa, the cloned CIA30 protein is reported as a globular protein
          preceded by a typical mitochondrial import sequence of 12 amino acids,
          supporting mitochondrial targeting and import.
- term:
    id: GO:0006120
    label: mitochondrial electron transport, NADH to ubiquinone
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for mitochondrial electron transport, NADH to ubiquinone. CIA30 is
      required for assembly of complex I, which performs NADH:ubiquinone oxidoreduction.
      Without CIA30, the large membrane arm intermediate cannot be formed, and the mature
      complex I is not assembled (PMID:9769214). CIA30 is not a subunit of the mature
      complex but is essential for its assembly. The IBA annotation is appropriate as
      CIA30 is involved in the pathway, albeit indirectly through its assembly function.
    action: ACCEPT
    reason: >-
      CIA30 is essential for complex I assembly (PMID:9769214). While not a subunit of
      the mature complex, its loss prevents proper complex I formation and thus NADH to
      ubiquinone electron transport. The IBA annotation appropriately captures this
      involvement.
    supported_by:
      - reference_id: PMID:9769214
        supporting_text: >-
          Mutants generated by disrupting the genes of either of the two proteins accumulate
          the matrix arm of complex I and the small membrane arm assembly intermediate, but are
          incapable of forming the large intermediate
- term:
    id: GO:0010257
    label: NADH dehydrogenase complex assembly
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for NADH dehydrogenase complex assembly. This is the core biological
      process function of CIA30. PMID:9769214 directly demonstrated that CIA30 is required
      for assembly of the large membrane arm intermediate of complex I, and pulse-chase
      experiments showed it participates in repeated assembly cycles. The IBA annotation is
      consistent with the NAS annotation for the more specific GO:0032981 term.
    action: ACCEPT
    reason: >-
      NADH dehydrogenase complex assembly is the core function of CIA30. Directly
      demonstrated by disruption mutants that fail to form the large membrane arm
      intermediate (PMID:9769214). The IBA is well supported and phylogenetically
      appropriate for the CIA30/NDUFAF1 family.
    additional_reference_ids:
      - file:NEUCR/cia30/cia30-deep-research-falcon.md
    supported_by:
      - reference_id: PMID:9769214
        supporting_text: >-
          Mutants generated by disrupting the genes of either of the two proteins accumulate
          the matrix arm of complex I and the small membrane arm assembly intermediate, but are
          incapable of forming the large intermediate
      - reference_id: PMID:9769214
        supporting_text: >-
          Pulse-chase labelling experiments showed that the two proteins are repeatedly involved
          in many assembly cycles of the intermediate
      - reference_id: file:NEUCR/cia30/cia30-deep-research-falcon.md
        supporting_text: >-
          Neurospora complex I assembly was established to occur stepwise from
          intermediates. CIA30 (together with CIA84) is associated with the large
          membrane-arm assembly intermediate and is not found in the mature complex I
          holoenzyme.
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for unfolded protein binding. GO:0051082 is proposed for obsoletion
      (go-ontology#30962). CIA30 was described as a "novel chaperone" in the original
      publication (PMID:9769214), but its function is specifically as a complex I assembly
      factor, not as a general unfolded protein binding protein. CIA30 associates exclusively
      with the large membrane arm assembly intermediate of complex I and participates in
      repeated assembly cycles (PMID:9769214). This is a specific assembly chaperone function
      rather than general unfolded protein binding. The term "chaperone" as used in the
      original paper refers to the specific assembly assistance role, not to broad unfolded
      protein recognition. Per UPB project rules, specific assembly chaperones that are not
      general unfolded protein binding proteins should be marked as over-annotated or
      modified.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      CIA30 is a specific complex I assembly factor, not a general unfolded protein binding
      protein. While described as a "chaperone" in PMID:9769214, this refers to its specific
      role in complex I membrane arm assembly -- it associates exclusively with the large
      membrane arm assembly intermediate and does not bind unfolded proteins generally. The
      GO:0051082 annotation overstates the generality of CIA30's binding specificity. The
      complex I assembly function is already captured by GO:0010257 and GO:0032981.
    additional_reference_ids:
      - file:NEUCR/cia30/cia30-deep-research-falcon.md
    supported_by:
      - reference_id: PMID:9769214
        supporting_text: >-
          In the wild-type, the extra proteins exclusively associate with the large membrane arm
          assembly intermediate
      - reference_id: PMID:9769214
        supporting_text: >-
          These results indicate that the two proteins are novel chaperones specific for complex
          I membrane arm assembly
      - reference_id: file:NEUCR/cia30/cia30-deep-research-falcon.md
        supporting_text: >-
          The strongest organism-specific evidence indicates CIA30 is imported into
          mitochondria, exists in free and assembly-bound pools, and binds transiently
          to a large membrane-arm assembly intermediate (not the mature holoenzyme).
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: >-
      IEA annotation for mitochondrion from UniProt subcellular location mapping. Consistent
      with the IBA annotation for the same term and the direct experimental evidence from
      PMID:9769214. UniProt lists mitochondrion as the subcellular location.
    action: ACCEPT
    reason: >-
      Consistent with IBA annotation and direct experimental evidence. Mitochondrion is
      the primary and only documented location of CIA30.
- term:
    id: GO:0032981
    label: mitochondrial respiratory chain complex I assembly
  evidence_type: NAS
  original_reference_id: PMID:9769214
  review:
    summary: >-
      NAS annotation for mitochondrial respiratory chain complex I assembly from PMID:9769214.
      This is the core biological process function of CIA30. The original paper titled
      "Involvement of two novel chaperones in the assembly of mitochondrial NADH:Ubiquinone
      oxidoreductase (complex I)" directly describes the role of CIA30 in complex I assembly.
      The NAS evidence code is appropriate as the paper provides direct experimental evidence
      for complex I assembly involvement. This is a more specific child of GO:0010257.
    action: ACCEPT
    reason: >-
      Complex I assembly is the core function of CIA30. PMID:9769214 directly demonstrated
      this through disruption mutants, pulse-chase experiments, and co-purification with
      assembly intermediates. This more specific term (child of GO:0010257) appropriately
      captures the respiratory chain complex I assembly function.
    supported_by:
      - reference_id: PMID:9769214
        supporting_text: >-
          These results indicate that the two proteins are novel chaperones specific for complex
          I membrane arm assembly
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IDA
  original_reference_id: PMID:9769214
  review:
    summary: >-
      IDA annotation for unfolded protein binding from PMID:9769214. GO:0051082 is proposed
      for obsoletion (go-ontology#30962). The original paper demonstrated that CIA30
      associates with the large membrane arm assembly intermediate of complex I and is
      involved in repeated assembly cycles (PMID:9769214: "the extra proteins exclusively
      associate with the large membrane arm assembly intermediate" and "Pulse-chase labelling
      experiments showed that the two proteins are repeatedly involved in many assembly
      cycles"). The authors called CIA30 a "chaperone" but specified it was "specific for
      complex I membrane arm assembly." This is a specific assembly factor function, not
      general unfolded protein binding. The protein does not bind unfolded proteins broadly
      -- it binds specifically to complex I assembly intermediates. The IDA evidence
      demonstrates complex I assembly intermediate binding, not general unfolded protein
      binding.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      The IDA evidence from PMID:9769214 demonstrates that CIA30 binds specifically to
      complex I assembly intermediates, not to unfolded proteins generally. The original
      paper explicitly states the proteins are "chaperones specific for complex I membrane
      arm assembly." GO:0051082 overstates the generality of the binding. The complex I
      assembly function is better captured by GO:0032981 and GO:0010257. While CIA30 may
      indeed interact with unfolded or partially assembled complex I subunits, calling
      this "unfolded protein binding" conflates a specific assembly factor role with
      general chaperone function.
    supported_by:
      - reference_id: PMID:9769214
        supporting_text: >-
          In the wild-type, the extra proteins exclusively associate with the large membrane arm
          assembly intermediate
      - reference_id: PMID:9769214
        supporting_text: >-
          Pulse-chase labelling experiments showed that the two proteins are repeatedly involved
          in many assembly cycles of the intermediate
      - reference_id: PMID:9769214
        supporting_text: >-
          These results indicate that the two proteins are novel chaperones specific for complex
          I membrane arm assembly
- term:
    id: GO:0044183
    label: protein folding chaperone
  evidence_type: NAS
  original_reference_id: PMID:9769214
  review:
    summary: >-
      New molecular-function annotation to capture CIA30's chaperone-like role in
      mitochondrial complex I assembly. The evidence supports a specific assembly
      chaperone activity for complex I membrane-arm intermediates, not broad
      unfolded-protein binding.
    action: NEW
    reason: >-
      GO:0044183 better reflects the core molecular function already summarized
      for CIA30 than GO:0051082. CIA30 is transiently associated with complex I
      assembly intermediates, is not a mature complex I subunit, and was described
      as a chaperone specific for complex I membrane arm assembly. This NEW
      annotation should be interpreted narrowly as assembly-chaperone activity for
      mitochondrial respiratory chain complex I biogenesis.
    additional_reference_ids:
      - file:NEUCR/cia30/cia30-deep-research-falcon.md
    supported_by:
      - reference_id: PMID:9769214
        supporting_text: >-
          These results indicate that the two proteins are novel chaperones specific for complex
          I membrane arm assembly
      - reference_id: file:NEUCR/cia30/cia30-deep-research-falcon.md
        supporting_text: >-
          CIA30 is a transient complex I assembly factor/chaperone, not a mature
          holoenzyme subunit. In N. crassa it associates with the large membrane-arm
          assembly intermediate and is released during assembly progression.
core_functions:
- molecular_function:
    id: GO:0044183
    label: protein folding chaperone
  description: >-
    CIA30 functions as a specific assembly chaperone for complex I membrane arm formation.
    It associates with the large membrane arm assembly intermediate and participates in
    repeated assembly cycles (PMID:9769214). The "chaperone" designation reflects its role
    in assisting complex I subunit assembly rather than general unfolded protein binding.
    While GO:0044183 is used as the closest available MF term, CIA30's function is more
    specifically as an assembly factor than as a general protein folding chaperone.
  directly_involved_in:
    - id: GO:0032981
      label: mitochondrial respiratory chain complex I assembly
    - id: GO:0006120
      label: mitochondrial electron transport, NADH to ubiquinone
  locations:
    - id: GO:0005739
      label: mitochondrion
  supported_by:
    - reference_id: PMID:9769214
      supporting_text: >-
        These results indicate that the two proteins are novel chaperones specific for complex
        I membrane arm assembly
    - reference_id: PMID:9769214
      supporting_text: >-
        Pulse-chase labelling experiments showed that the two proteins are repeatedly involved
        in many assembly cycles of the intermediate
references:
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: PMID:9769214
  title: Involvement of two novel chaperones in the assembly of mitochondrial NADH:Ubiquinone
    oxidoreductase (complex I).
  findings: []
- id: file:NEUCR/cia30/cia30-deep-research-falcon.md
  title: Deep research report on cia30 (Falcon/Edison Scientific Literature)
  findings:
  - statement: cia30 is the Neurospora crassa complex I assembly factor (CIA30/NDUFAF1 ortholog) that chaperones the assembly of the mitochondrial NADH:ubiquinone oxidoreductase (Complex I) by stabilizing early subassembly intermediates.