TIMM23 encodes an essential inner mitochondrial membrane core subunit of the TIM23 presequence translocase. Together with TIMM17A/B and TIMM50, it supports import of nuclear-encoded, presequence-containing mitochondrial proteins into the matrix and lateral insertion of selected inner-membrane proteins; it also has a supported non-core role in PINK1-linked stress-induced mitophagy.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0030150
protein import into mitochondrial matrix
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Correct and core. TIMM23-containing TIM23 translocase imports presequence-containing proteins into the mitochondrial matrix.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
Most mitochondrial proteins are nuclear encoded and must be imported into mitochondria. The **TIM23 complex** (also called the **presequence translocase**) is the major inner-membrane translocase for **presequence-containing precursor proteins**, handling a large fraction of mitochondrial protein biogenesis.
|
|
GO:0005744
TIM23 mitochondrial import inner membrane translocase complex
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
|
|
GO:0008320
protein transmembrane transporter activity
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Accepted as TIMM23 contribution to TIM23-dependent protein translocation across the mitochondrial inner membrane. TIMM23 is essential in the translocase core, even though recent structural work emphasizes Tim17-family subunits as the dominant translocation cavity.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
**TIMM23 is essential** within the TIM23 presequence translocase core, but **Tim17-family proteins** appear to provide the dominant **translocation cavity** driven by conserved electrostatics (negative charges).
|
|
GO:0005743
mitochondrial inner membrane
|
IEA
GO_REF:0000044 |
ACCEPT |
Summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
|
|
GO:0005744
TIM23 mitochondrial import inner membrane translocase complex
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
|
|
GO:0008320
protein transmembrane transporter activity
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: Accepted as TIMM23 contribution to TIM23-dependent protein translocation across the mitochondrial inner membrane. TIMM23 is essential in the translocase core, even though recent structural work emphasizes Tim17-family subunits as the dominant translocation cavity.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
**TIMM23 is essential** within the TIM23 presequence translocase core, but **Tim17-family proteins** appear to provide the dominant **translocation cavity** driven by conserved electrostatics (negative charges).
|
|
GO:0022857
transmembrane transporter activity
|
IEA
GO_REF:0000002 |
MARK AS OVER ANNOTATED |
Summary: Correct but too broad; the more specific supported function is protein transmembrane transporter activity in the TIM23 presequence translocase.
Reason: Use GO:0008320 protein transmembrane transporter activity and TIM23 complex annotations rather than generic transmembrane transporter activity.
|
|
GO:0030150
protein import into mitochondrial matrix
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: Correct and core. TIMM23-containing TIM23 translocase imports presequence-containing proteins into the mitochondrial matrix.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
Most mitochondrial proteins are nuclear encoded and must be imported into mitochondria. The **TIM23 complex** (also called the **presequence translocase**) is the major inner-membrane translocase for **presequence-containing precursor proteins**, handling a large fraction of mitochondrial protein biogenesis.
|
|
GO:0005515
protein binding
|
IPI
PMID:23260140 MITRAC links mitochondrial protein translocation to respirat... |
MARK AS OVER ANNOTATED |
Summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
Reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
|
|
GO:0005515
protein binding
|
IPI
PMID:23263864 Methylation-controlled J-protein MCJ acts in the import of p... |
MARK AS OVER ANNOTATED |
Summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
Reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
|
|
GO:0005515
protein binding
|
IPI
PMID:32296183 A reference map of the human binary protein interactome. |
MARK AS OVER ANNOTATED |
Summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
Reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
|
|
GO:0005515
protein binding
|
IPI
PMID:32814053 Interactome Mapping Provides a Network of Neurodegenerative ... |
MARK AS OVER ANNOTATED |
Summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
Reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
|
|
GO:0008320
protein transmembrane transporter activity
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: Accepted as TIMM23 contribution to TIM23-dependent protein translocation across the mitochondrial inner membrane. TIMM23 is essential in the translocase core, even though recent structural work emphasizes Tim17-family subunits as the dominant translocation cavity.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
**TIMM23 is essential** within the TIM23 presequence translocase core, but **Tim17-family proteins** appear to provide the dominant **translocation cavity** driven by conserved electrostatics (negative charges).
|
|
GO:0005743
mitochondrial inner membrane
|
NAS
PMID:10339406 Genetic and structural characterization of the human mitocho... |
ACCEPT |
Summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
|
|
GO:0005744
TIM23 mitochondrial import inner membrane translocase complex
|
NAS
PMID:10339406 Genetic and structural characterization of the human mitocho... |
ACCEPT |
Summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
|
|
GO:0006886
intracellular protein transport
|
NAS
PMID:10339406 Genetic and structural characterization of the human mitocho... |
MARK AS OVER ANNOTATED |
Summary: Correct but broad. TIMM23 is specifically involved in mitochondrial protein import via the TIM23 presequence translocase.
Reason: The specific mitochondrial matrix import and TIM23 translocase terms capture the supported biology better than generic intracellular protein transport.
|
|
GO:0030150
protein import into mitochondrial matrix
|
TAS
PMID:10339406 Genetic and structural characterization of the human mitocho... |
ACCEPT |
Summary: Correct and core. TIMM23-containing TIM23 translocase imports presequence-containing proteins into the mitochondrial matrix.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
Most mitochondrial proteins are nuclear encoded and must be imported into mitochondria. The **TIM23 complex** (also called the **presequence translocase**) is the major inner-membrane translocase for **presequence-containing precursor proteins**, handling a large fraction of mitochondrial protein biogenesis.
|
|
GO:0005739
mitochondrion
|
IDA
GO_REF:0000052 |
MARK AS OVER ANNOTATED |
Summary: Correct but broad. TIMM23 is specifically localized to the mitochondrial inner membrane and TIM23 complex.
Reason: Prefer mitochondrial inner membrane/TIM23 complex annotations over generic mitochondrion.
|
|
GO:0005739
mitochondrion
|
HTP
PMID:34800366 Quantitative high-confidence human mitochondrial proteome an... |
MARK AS OVER ANNOTATED |
Summary: Correct but broad. TIMM23 is specifically localized to the mitochondrial inner membrane and TIM23 complex.
Reason: Prefer mitochondrial inner membrane/TIM23 complex annotations over generic mitochondrion.
|
|
GO:0005515
protein binding
|
IPI
PMID:37160114 TIM23 facilitates PINK1 activation by safeguarding against O... |
MARK AS OVER ANNOTATED |
Summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
Reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
|
|
GO:0061734
type 2 mitophagy
|
IMP
PMID:37160114 TIM23 facilitates PINK1 activation by safeguarding against O... |
KEEP AS NON CORE |
Summary: Supported as a non-core stress-response role. TIMM23 can help PINK1 accumulate during depolarization-linked mitophagy, but its primary function is TIM23 presequence translocase protein import.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
Has a role in the activation of stress-induced mitophagy by protecting PINK1 from OMA1-mediated degradation and facilitating its accumulation at the outer mitochondrial membrane in response to depolarization
|
|
GO:0005744
TIM23 mitochondrial import inner membrane translocase complex
|
IDA
PMID:30598479 ROMO1 is a constituent of the human presequence translocase ... |
ACCEPT |
Summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
|
|
GO:0005743
mitochondrial inner membrane
|
IDA
PMID:25997101 QIL1 is a novel mitochondrial protein required for MICOS com... |
ACCEPT |
Summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
|
|
GO:0005743
mitochondrial inner membrane
|
IDA
PMID:20053669 Role of Magmas in protein transport and human mitochondria b... |
ACCEPT |
Summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
|
|
GO:0005743
mitochondrial inner membrane
|
IDA
PMID:10339406 Genetic and structural characterization of the human mitocho... |
ACCEPT |
Summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
|
|
GO:0005744
TIM23 mitochondrial import inner membrane translocase complex
|
IDA
PMID:10339406 Genetic and structural characterization of the human mitocho... |
ACCEPT |
Summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
|
|
GO:0005743
mitochondrial inner membrane
|
TAS
PMID:14726512 Organization and function of the small Tim complexes acting ... |
ACCEPT |
Summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
|
|
GO:0005515
protein binding
|
IPI
PMID:15044455 Tim50, a component of the mitochondrial translocator, regula... |
MARK AS OVER ANNOTATED |
Summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
Reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
|
|
GO:0005758
mitochondrial intermembrane space
|
IDA
PMID:15044455 Tim50, a component of the mitochondrial translocator, regula... |
ACCEPT |
Summary: Supported. TIMM23 has an intermembrane-space-facing region within the inner-membrane TIM23 machinery.
Supporting Evidence:
file:human/TIMM23/TIMM23-deep-research-falcon.md
TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
|
Q: Which human TIMM23-containing TIM23 cores differ functionally between TIMM17A and TIMM17B paralog contexts?
Q: How separable is TIMM23 structural support of the presequence translocase from its PINK1-linked mitophagy role under depolarizing stress?
Experiment: Use TIMM23 interface mutants in rescue cells and compare TIM23 complex assembly, matrix import substrates, TIM23SORT substrates, and Tim17/TIMM50 interactions by BN-PAGE and in vitro import assays.
Hypothesis: TIMM23 contributes primarily as an essential structural/regulatory core subunit while TIMM17-family proteins form the dominant presequence translocation cavity.
Experiment: Test TIMM23 mutants that preserve TIM23 complex assembly but disrupt PINK1 association, then measure PINK1 stabilization, PRKN recruitment, and matrix/import substrate flux.
Hypothesis: TIMM23-PINK1 interaction during mitochondrial depolarization is a stress-specific function separable from basal TIM23 import.
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.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
The research target is human TIMM23 (gene symbol TIMM23/TIM23), UniProt O14925, annotated as โmitochondrial import inner membrane translocase subunit Tim23โ and belonging to the Tim17/Tim22/Tim23 family. A 2024 human-focused structural modeling study explicitly uses hTIMM23 (UniProt O14925) as input for modeling the human core TIM23 translocase, confirming that the literature summarized here concerns the intended protein identity and organism (Homo sapiens). (maruszczak2024structurepredictionanalysis pages 2-3)
Most mitochondrial proteins are nuclear encoded and must be imported into mitochondria. The TIM23 complex (also called the presequence translocase) is the major inner-membrane translocase for presequence-containing precursor proteins, handling a large fraction of mitochondrial protein biogenesis. Current reviews and primary disease-mechanism work estimate that the TOMโTIM23 route delivers ~60% of the mitochondrial proteome, covering the majority of matrix proteins and many inner membrane proteins (and some IMS proteins). (jain2024hotspotsfordiseasecausing pages 2-4, crameri2024reducedproteinimport pages 1-3, jain2024hotspotsfordiseasecausing pages 1-2)
TIMM23 is a core subunit of the TIM23 inner membrane translocase. It functions in protein translocation/sorting by forming a conserved core with Tim17-family subunits and coordinating with the IMS receptor subunit Tim50 and with accessory modules that determine whether a precursor is:
- fully translocated into the matrix, or
- laterally inserted (stop-transfer) into the inner mitochondrial membrane.
Human TIM23 core composition is typically described as TIMM23 + TIMM17A/B + TIMM50, which dynamically associates with additional factors depending on the substrate and import mode. (crameri2024reducedproteinimport pages 1-3, jain2024hotspotsfordiseasecausing pages 11-12)
Human TIM23 is frequently conceptualized as operating in two functional configurations:
- TIM23MOTOR: coupled to the presequence translocase-associated motor (PAM-like), driving complete translocation into the matrix via ATP-dependent chaperone activity.
- TIM23SORT: enabling lateral release of membrane proteins into the inner membrane.
A 2024 human study of TIM23 dysfunction in TIMM50-associated mitochondrial disease provides a clear, experimentally grounded description of these modules and their component sets. (crameri2024reducedproteinimport pages 1-3, crameri2024reducedproteinimport pages 11-12)
Two 2023 Nature studies in yeast (highly informative for the conserved core mechanism) revise the classical idea that Tim23 alone forms the translocation pore:
- The TIM23 core is supported as a Tim17โTim23 1:1 heterodimer arranged back-to-back in the idle state, arguing against stable Tim23 homo-oligomeric pore models. (sim2023structuralbasisof pages 1-4)
- Mechanistic mapping of arrested precursors indicates that Tim17 provides the principal lateral transmembrane cavity for presequence translocation; the initiating interaction is driven by conserved negative charges (an acidic patch on the IMS side) that attract positively charged presequences. (fielden2023centralroleof pages 9-11, fielden2023centralroleof pages 11-13, fielden2023centralroleof pages 7-9)
These studies support a model where TIMM23 remains essential but is increasingly interpreted as structural/regulatory within the core, while the primary translocation environment is centered on Tim17-family proteins. (fielden2023centralroleof pages 7-9, sim2023structuralbasisof pages 1-4)
A 2024 human-focused structure prediction analysis (AlphaFold/ColabFold multimer) models the human core TIM23 using hTIMM23 (O14925) along with TIMM17A or TIMM17B, ROMO1, and TIMM44, and reports that the predicted human core is highly similar to yeast Tim17โTim23 cryo-EM structures. (maruszczak2024structurepredictionanalysis pages 2-3, maruszczak2024structurepredictionanalysis pages 3-5)
The same work highlights conservation of key functional features implicated by 2023 mechanistic studies (e.g., electrostatic/hydrophobic character of the translocation cavity, including an acidic patch on the IMS side relevant to presequence capture), supporting mechanistic transferability from yeast Tim17/Tim23 to human TIMM17/TIMM23. (maruszczak2024structurepredictionanalysis pages 2-3, maruszczak2024structurepredictionanalysis pages 3-5)
Recent human disease-mechanism work and a 2024 disease-genetics mini-review converge on the following interacting partners/modules:
Core TIM23 (inner membrane):
- TIMM23 (O14925)
- TIMM17A or TIMM17B (two paralog-based pools)
- TIMM50 (IMS receptor; required for proper complex function)
TIM23MOTOR (matrix translocation):
- TIMM44, HSPA9 (mtHsp70/mortalin), PAM16, GRPEL1/2, and DNAJC co-chaperones (DNAJC19/15) (crameri2024reducedproteinimport pages 1-3, jain2024hotspotsfordiseasecausing pages 2-4)
TIM23SORT (inner membrane insertion):
- TIMM21 and ROMO1 (crameri2024reducedproteinimport pages 1-3)
A key mechanistic point emphasized in expert synthesis is that Tim23โTim50 interaction is essential for protein translocation, coordinating receptor/channel/motor functions across import steps. (jain2024hotspotsfordiseasecausing pages 11-12)
Fielden et al. (Nature, Aug 2023) provide direct evidence that conserved negative charges in Tim17 are essential to initiate translocation; combined mutations strongly impair presequence import while not collapsing membrane potential or TIM22-dependent assembly, supporting a specific TIM23-core functional defect mechanism. (fielden2023centralroleof pages 9-11, fielden2023centralroleof pages 7-9)
Sim et al. (Nature, Jun 2023) support a stable Tim17โTim23 heterodimer and propose a laterally open Tim17 cavity enclosed by Mgr2 as a plausible translocation route, challenging simplified โaqueous pore by Tim23 aloneโ models. (sim2023structuralbasisof pages 1-4)
Maruszczak et al. (FEBS Open Bio, Jun 2024) report two highly similar human core TIM23 populations containing TIMM23 + TIMM17A or TIMM23 + TIMM17B, with high structural similarity to yeast Tim17โTim23. They propose that functional differences between TIMM17A- and TIMM17B-based translocases likely arise from regulatory factors rather than large structural divergence, and note involvement of ROMO1 as an associated factor in the modeled core. (maruszczak2024structurepredictionanalysis pages 1-2, maruszczak2024structurepredictionanalysis pages 3-5, maruszczak2024structurepredictionanalysis pages 9-11)
A 2024 mini-review synthesizing disease-causing variants across the TIM23 system concludes that, among core components, TIMM50 is a prominent hotspot for disease-causing mutations, and that PAM/mortalin (mtHsp70) plus its J-domain regulators are also hotspots. The clinical phenotypes are summarized as predominantly early-age developmental and neurological defects, consistent with essential roles in mitochondrial biogenesis. (jain2024hotspotsfordiseasecausing pages 1-2)
Notably, within the gathered evidence, specific disease-causing variants are emphasized for TIMM50 rather than TIMM23 itself, implying that (as of these sources) TIMM23 may be less frequently reported as a primary Mendelian disease gene compared with TIMM50/PAM components, even though TIMM23 is an essential core subunit. (jain2024hotspotsfordiseasecausing pages 1-2, crameri2024reducedproteinimport pages 1-3)
Crameri et al. (Molecular and Cellular Biology, Jun 2024) demonstrate a clinically anchored workflow for mechanistic resolution of mitochondrial disease caused by TIM23-pathway dysfunction:
- patient-derived cells and engineered cell models,
- BN-PAGE assessment of TIM23 complex integrity,
- quantitative proteomics to map proteome vulnerabilities,
- in vitro import assays to separate TIM23MOTOR vs TIM23SORT functional impacts.
This represents a direct real-world implementation of TIM23 biology in mitochondrial disease mechanism discovery. (crameri2024reducedproteinimport pages 1-3, crameri2024reducedproteinimport pages 11-12)
Maruszczak et al. (Jun 2024) exemplify the use of AlphaFold-multimer/ColabFold to model human TIM23 core assemblies with UniProt-defined sequences (including TIMM23 O14925), enabling mapping of conserved functional features and prioritization of regulatory hypotheses for TIMM17A vs TIMM17B-containing complexes. (maruszczak2024structurepredictionanalysis pages 2-3, maruszczak2024structurepredictionanalysis pages 9-11)
Recent expert synthesis and primary disease-mechanism work reiterate that the TOMโTIM23 pathway imports ~60% of the mitochondrial proteome, and anchors this estimate to a human mitochondrial proteome of roughly ~1,100โ1,500 proteins (13 mtDNA-encoded). (jain2024hotspotsfordiseasecausing pages 1-2, crameri2024reducedproteinimport pages 1-3)
In TIMM50-associated disease models where TIM23 complex levels/activity are reduced, Crameri et al. quantify in vitro import decreases:
- TIM23MOTOR substrate OTC import reduced to ~82% of control
- TIM23SORT substrates: SURF1 ~67% of control, SCO2 ~62% of control
They also report that TIM22-pathway substrates (n = 58) were largely unchanged, supporting specificity for TIM23 pathway dysfunction. (crameri2024reducedproteinimport pages 11-12)
These measurements provide an experimentally grounded, quantitative view of how disruption of a core TIM23 component (TIMM50) propagates to functional impairment of the TIMM23-containing translocase and reveals substrate-class sensitivity. (crameri2024reducedproteinimport pages 11-12)
Integrating 2023 structure/mechanism papers and 2024 human modeling and disease analyses supports the following interpretation:
1) TIMM23 is essential within the TIM23 presequence translocase core, but Tim17-family proteins appear to provide the dominant translocation cavity driven by conserved electrostatics (negative charges). (fielden2023centralroleof pages 9-11, fielden2023centralroleof pages 7-9, sim2023structuralbasisof pages 1-4)
2) TIMM23 likely plays a structural/regulatory role within the heterodimeric core and in coordinating accessory modules, consistent with the back-to-back heterodimer architecture and the difficulty of reconciling Tim23-only pore models with native structural observations. (sim2023structuralbasisof pages 1-4, fielden2023centralroleof pages 7-9)
3) In humans, the presence of two paralog-based cores (TIMM17A vs TIMM17B) suggests that regulation (stress responsiveness, complex stability, accessory binding) may tune import capacity without major remodeling of TIMM23 itself. (maruszczak2024structurepredictionanalysis pages 3-5, maruszczak2024structurepredictionanalysis pages 9-11)
The 2024 review framing TIMM50 as a mutation hotspot, and the 2024 patient-centered TIMM50 study, both emphasize that mutations in one TIM23 component can reduce the steady-state levels/activity of the overall complex (including TIMM23), producing multisystem mitochondrial pathologyโthus TIMM23 function is clinically relevant even when TIMM23 is not the primary mutated gene. (jain2024hotspotsfordiseasecausing pages 1-2, crameri2024reducedproteinimport pages 1-3, crameri2024reducedproteinimport pages 11-12)
The following figures from the 2024 human modeling study illustrate the subunit set of the human TIM23 complex and structural context for ROMO1 and the TIMM17 paralog variants, providing a visual anchor for TIMM23-centered functional annotation. (maruszczak2024structurepredictionanalysis media e620fbb9, maruszczak2024structurepredictionanalysis media 460c7670, maruszczak2024structurepredictionanalysis media 2ee6cbee)
| Aspect | Key points (1-2 sentences) | Best recent sources (with year) | URL/DOI |
|---|---|---|---|
| Identity/Localization | TIMM23 is the human inner mitochondrial membrane subunit of the TIM23/presequence translocase; the 2024 human structure-prediction study explicitly models hTIMM23 using UniProt O14925. Human core TIM23 complexes contain TIMM23 with either TIMM17A or TIMM17B and show strong conservation with yeast architecture. (maruszczak2024structurepredictionanalysis pages 2-3, maruszczak2024structurepredictionanalysis pages 1-2) | Maruszczak et al., 2024; Jain et al., 2024 | https://doi.org/10.1002/2211-5463.13840; https://doi.org/10.3390/genes15121534 |
| Core function | TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane. Reviews estimate this pathway handles ~60% of the mitochondrial proteome, including most matrix proteins and many inner-membrane proteins. (jain2024hotspotsfordiseasecausing pages 2-4, jain2024hotspotsfordiseasecausing pages 1-2) | Jain et al., 2024; Crameri et al., 2024 | https://doi.org/10.3390/genes15121534; https://doi.org/10.1080/10985549.2024.2353652 |
| Complex modules | Human TIM23 operates in at least two functional states: TIM23MOTOR for matrix translocation and TIM23SORT for lateral insertion of inner-membrane proteins. TIM23MOTOR includes DNAJC19/15, TIMM44, HSPA9, PAM16, and GRPEL1/2, whereas TIM23SORT includes TIMM21 and ROMO1. (jain2024hotspotsfordiseasecausing pages 2-4, crameri2024reducedproteinimport pages 1-3) | Crameri et al., 2024; Jain et al., 2024 | https://doi.org/10.1080/10985549.2024.2353652; https://doi.org/10.3390/genes15121534 |
| Key partners | Core/associated partners include TIMM17A or TIMM17B, TIMM50, TIMM21, ROMO1, TIMM44, mtHsp70/HSPA9, PAM16, DNAJC19/15, and GRPEL1/2. TIM23โTim50 interaction is highlighted as essential for protein translocation and coordination of receptor, channel, and motor functions. (jain2024hotspotsfordiseasecausing pages 11-12, maruszczak2024structurepredictionanalysis pages 2-3) | Jain et al., 2024; Maruszczak et al., 2024 | https://doi.org/10.3390/genes15121534; https://doi.org/10.1002/2211-5463.13840 |
| Mechanistic insights from 2023 Nature structures | 2023 structural/mechanistic work revised the classic view of the pore: Tim17 and Tim23 form a back-to-back heterodimer, and Tim17 appears to provide the principal lateral translocation cavity. Conserved negative charges in Tim17 are required to initiate presequence movement, while Tim23 is increasingly interpreted as having essential structural/regulatory roles rather than being the sole translocation channel. (sim2023structuralbasisof pages 1-4, fielden2023centralroleof pages 9-11, fielden2023centralroleof pages 7-9) | Sim et al., 2023; Fielden et al., 2023 | https://doi.org/10.1038/s41586-023-06239-6; https://doi.org/10.1038/s41586-023-06477-8 |
| Human-specific variants/regulation | Human cells contain two highly similar core TIM23 populations with TIMM17A- or TIMM17B-containing complexes; predicted structures suggest differences are more likely regulatory than architectural. TIMM17B-containing complexes are described as more housekeeping/import-competent, whereas TIMM17A is stress-sensitive and has been linked to cancer-associated regulation; ROMO1 is the likely human Mgr2 counterpart. (maruszczak2024structurepredictionanalysis pages 3-5, maruszczak2024structurepredictionanalysis pages 2-3, maruszczak2024structurepredictionanalysis pages 11-12, maruszczak2024structurepredictionanalysis pages 9-11, jain2024hotspotsfordiseasecausing pages 2-4) | Maruszczak et al., 2024; Jain et al., 2024 | https://doi.org/10.1002/2211-5463.13840; https://doi.org/10.3390/genes15121534 |
| Disease associations | Recent reviews of TIM23-complex disease genetics emphasize TIMM50 and PAM/mortalin-related components as mutation hotspots causing mainly early developmental and neurological disease; disease-causing TIMM23 variants themselves were not detailed in the gathered evidence. TIMM50 dysfunction secondarily lowers TIMM23-complex levels/activity and drives mitochondrial disease pathology. (crameri2024reducedproteinimport pages 1-3, jain2024hotspotsfordiseasecausing pages 1-2, crameri2024reducedproteinimport pages 11-12) | Jain et al., 2024; Crameri et al., 2024 | https://doi.org/10.3390/genes15121534; https://doi.org/10.1080/10985549.2024.2353652 |
| Quantitative data/stats | The TIM23 pathway is estimated to import ~60% of the ~1,100-1,500 mitochondrial proteome. In TIMM50-deficient human disease models, in vitro import fell to ~82% of control for the TIM23MOTOR substrate OTC and to ~67% and ~62% for TIM23SORT substrates SURF1 and SCO2, while TIM22-pathway substrates (n=58) were largely unchanged. (crameri2024reducedproteinimport pages 1-3, jain2024hotspotsfordiseasecausing pages 1-2, crameri2024reducedproteinimport pages 11-12) | Crameri et al., 2024; Jain et al., 2024 | https://doi.org/10.1080/10985549.2024.2353652; https://doi.org/10.3390/genes15121534 |
| Applications/assays | Current implementations are mainly mechanistic and translational: AlphaFold/ColabFold modeling of human TIM23 architecture, BN-PAGE/steady-state complex analysis, radiolabeled in vitro import assays, and quantitative proteomics to map pathway-specific substrate vulnerability in disease. These approaches are already being used to dissect TIM23SORT versus TIM23MOTOR defects in human mitochondrial disorders. (crameri2024reducedproteinimport pages 1-3, crameri2024reducedproteinimport pages 11-12, maruszczak2024structurepredictionanalysis pages 2-3) | Crameri et al., 2024; Maruszczak et al., 2024 | https://doi.org/10.1080/10985549.2024.2353652; https://doi.org/10.1002/2211-5463.13840 |
Table: This table summarizes the supported functional annotation of human TIMM23 (UniProt O14925), emphasizing localization, molecular role in the TIM23 complex, recent 2023-2024 mechanistic insights, disease relevance, and quantitative findings. It is useful as a concise evidence-backed overview for report writing or annotation review.
References
(maruszczak2024structurepredictionanalysis pages 2-3): Klaudia K. Maruszczak, Piotr Draczkowski, Artur Wnorowski, and Agnieszka Chacinska. Structure prediction analysis of human core tim23 complex reveals conservation of the protein translocation mechanism. FEBS Open Bio, 14:1656-1667, Jun 2024. URL: https://doi.org/10.1002/2211-5463.13840, doi:10.1002/2211-5463.13840. This article has 13 citations and is from a peer-reviewed journal.
(jain2024hotspotsfordiseasecausing pages 2-4): Sahil Jain, Eyal Paz, and Abdussalam Azem. Hotspots for disease-causing mutations in the mitochondrial tim23 import complex. Genes, 15:1534, Nov 2024. URL: https://doi.org/10.3390/genes15121534, doi:10.3390/genes15121534. This article has 1 citations.
(crameri2024reducedproteinimport pages 1-3): Jordan J. Crameri, Catherine S. Palmer, Tegan Stait, Thomas D. Jackson, Matthew Lynch, Adriane Sinclair, Leah E. Frajman, Alison G. Compton, David Coman, David R. Thorburn, Ann E. Frazier, and Diana Stojanovski. Reduced protein import via tim23 sort drives disease pathology in timm50-associated mitochondrial disease. Molecular and Cellular Biology, 44:226-244, Jun 2024. URL: https://doi.org/10.1080/10985549.2024.2353652, doi:10.1080/10985549.2024.2353652. This article has 9 citations and is from a domain leading peer-reviewed journal.
(jain2024hotspotsfordiseasecausing pages 1-2): Sahil Jain, Eyal Paz, and Abdussalam Azem. Hotspots for disease-causing mutations in the mitochondrial tim23 import complex. Genes, 15:1534, Nov 2024. URL: https://doi.org/10.3390/genes15121534, doi:10.3390/genes15121534. This article has 1 citations.
(jain2024hotspotsfordiseasecausing pages 11-12): Sahil Jain, Eyal Paz, and Abdussalam Azem. Hotspots for disease-causing mutations in the mitochondrial tim23 import complex. Genes, 15:1534, Nov 2024. URL: https://doi.org/10.3390/genes15121534, doi:10.3390/genes15121534. This article has 1 citations.
(crameri2024reducedproteinimport pages 11-12): Jordan J. Crameri, Catherine S. Palmer, Tegan Stait, Thomas D. Jackson, Matthew Lynch, Adriane Sinclair, Leah E. Frajman, Alison G. Compton, David Coman, David R. Thorburn, Ann E. Frazier, and Diana Stojanovski. Reduced protein import via tim23 sort drives disease pathology in timm50-associated mitochondrial disease. Molecular and Cellular Biology, 44:226-244, Jun 2024. URL: https://doi.org/10.1080/10985549.2024.2353652, doi:10.1080/10985549.2024.2353652. This article has 9 citations and is from a domain leading peer-reviewed journal.
(sim2023structuralbasisof pages 1-4): Sue Im Sim, Yuanyuan Chen, Diane L. Lynch, James C. Gumbart, and Eunyong Park. Structural basis of mitochondrial protein import by the tim23 complex. Nature, 621:620-626, Jun 2023. URL: https://doi.org/10.1038/s41586-023-06239-6, doi:10.1038/s41586-023-06239-6. This article has 105 citations and is from a highest quality peer-reviewed journal.
(fielden2023centralroleof pages 9-11): Laura F. Fielden, Jakob D. Busch, Sandra G. Merkt, Iniyan Ganesan, Conny Steiert, Hanna B. Hasselblatt, Jon V. Busto, Christophe Wirth, Nicole Zufall, Sibylle Jungbluth, Katja Noll, Julia M. Dung, Ludmila Butenko, Karina von der Malsburg, Hans-Georg Koch, Carola Hunte, Martin van der Laan, and Nils Wiedemann. Central role of tim17 in mitochondrial presequence protein translocation. Nature, 621:627-634, Aug 2023. URL: https://doi.org/10.1038/s41586-023-06477-8, doi:10.1038/s41586-023-06477-8. This article has 64 citations and is from a highest quality peer-reviewed journal.
(fielden2023centralroleof pages 11-13): Laura F. Fielden, Jakob D. Busch, Sandra G. Merkt, Iniyan Ganesan, Conny Steiert, Hanna B. Hasselblatt, Jon V. Busto, Christophe Wirth, Nicole Zufall, Sibylle Jungbluth, Katja Noll, Julia M. Dung, Ludmila Butenko, Karina von der Malsburg, Hans-Georg Koch, Carola Hunte, Martin van der Laan, and Nils Wiedemann. Central role of tim17 in mitochondrial presequence protein translocation. Nature, 621:627-634, Aug 2023. URL: https://doi.org/10.1038/s41586-023-06477-8, doi:10.1038/s41586-023-06477-8. This article has 64 citations and is from a highest quality peer-reviewed journal.
(fielden2023centralroleof pages 7-9): Laura F. Fielden, Jakob D. Busch, Sandra G. Merkt, Iniyan Ganesan, Conny Steiert, Hanna B. Hasselblatt, Jon V. Busto, Christophe Wirth, Nicole Zufall, Sibylle Jungbluth, Katja Noll, Julia M. Dung, Ludmila Butenko, Karina von der Malsburg, Hans-Georg Koch, Carola Hunte, Martin van der Laan, and Nils Wiedemann. Central role of tim17 in mitochondrial presequence protein translocation. Nature, 621:627-634, Aug 2023. URL: https://doi.org/10.1038/s41586-023-06477-8, doi:10.1038/s41586-023-06477-8. This article has 64 citations and is from a highest quality peer-reviewed journal.
(maruszczak2024structurepredictionanalysis pages 3-5): Klaudia K. Maruszczak, Piotr Draczkowski, Artur Wnorowski, and Agnieszka Chacinska. Structure prediction analysis of human core tim23 complex reveals conservation of the protein translocation mechanism. FEBS Open Bio, 14:1656-1667, Jun 2024. URL: https://doi.org/10.1002/2211-5463.13840, doi:10.1002/2211-5463.13840. This article has 13 citations and is from a peer-reviewed journal.
(maruszczak2024structurepredictionanalysis pages 1-2): Klaudia K. Maruszczak, Piotr Draczkowski, Artur Wnorowski, and Agnieszka Chacinska. Structure prediction analysis of human core tim23 complex reveals conservation of the protein translocation mechanism. FEBS Open Bio, 14:1656-1667, Jun 2024. URL: https://doi.org/10.1002/2211-5463.13840, doi:10.1002/2211-5463.13840. This article has 13 citations and is from a peer-reviewed journal.
(maruszczak2024structurepredictionanalysis pages 9-11): Klaudia K. Maruszczak, Piotr Draczkowski, Artur Wnorowski, and Agnieszka Chacinska. Structure prediction analysis of human core tim23 complex reveals conservation of the protein translocation mechanism. FEBS Open Bio, 14:1656-1667, Jun 2024. URL: https://doi.org/10.1002/2211-5463.13840, doi:10.1002/2211-5463.13840. This article has 13 citations and is from a peer-reviewed journal.
(maruszczak2024structurepredictionanalysis media e620fbb9): Klaudia K. Maruszczak, Piotr Draczkowski, Artur Wnorowski, and Agnieszka Chacinska. Structure prediction analysis of human core tim23 complex reveals conservation of the protein translocation mechanism. FEBS Open Bio, 14:1656-1667, Jun 2024. URL: https://doi.org/10.1002/2211-5463.13840, doi:10.1002/2211-5463.13840. This article has 13 citations and is from a peer-reviewed journal.
(maruszczak2024structurepredictionanalysis media 460c7670): Klaudia K. Maruszczak, Piotr Draczkowski, Artur Wnorowski, and Agnieszka Chacinska. Structure prediction analysis of human core tim23 complex reveals conservation of the protein translocation mechanism. FEBS Open Bio, 14:1656-1667, Jun 2024. URL: https://doi.org/10.1002/2211-5463.13840, doi:10.1002/2211-5463.13840. This article has 13 citations and is from a peer-reviewed journal.
(maruszczak2024structurepredictionanalysis media 2ee6cbee): Klaudia K. Maruszczak, Piotr Draczkowski, Artur Wnorowski, and Agnieszka Chacinska. Structure prediction analysis of human core tim23 complex reveals conservation of the protein translocation mechanism. FEBS Open Bio, 14:1656-1667, Jun 2024. URL: https://doi.org/10.1002/2211-5463.13840, doi:10.1002/2211-5463.13840. This article has 13 citations and is from a peer-reviewed journal.
(maruszczak2024structurepredictionanalysis pages 11-12): Klaudia K. Maruszczak, Piotr Draczkowski, Artur Wnorowski, and Agnieszka Chacinska. Structure prediction analysis of human core tim23 complex reveals conservation of the protein translocation mechanism. FEBS Open Bio, 14:1656-1667, Jun 2024. URL: https://doi.org/10.1002/2211-5463.13840, doi:10.1002/2211-5463.13840. This article has 13 citations and is from a peer-reviewed journal.
id: O14925
gene_symbol: TIMM23
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:9606
label: Homo sapiens
description: TIMM23 encodes an essential inner mitochondrial membrane core subunit of the TIM23 presequence translocase. Together with TIMM17A/B and TIMM50, it supports import of nuclear-encoded, presequence-containing mitochondrial proteins into the matrix and lateral insertion of selected inner-membrane proteins; it also has a supported non-core role in PINK1-linked stress-induced mitophagy.
existing_annotations:
- term:
id: GO:0030150
label: protein import into mitochondrial matrix
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: Correct and core. TIMM23-containing TIM23 translocase imports presequence-containing proteins into the mitochondrial matrix.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: Most mitochondrial proteins are nuclear encoded and must be imported into mitochondria. The **TIM23 complex** (also called the **presequence translocase**) is the major inner-membrane translocase for **presequence-containing precursor proteins**, handling a large fraction of mitochondrial protein biogenesis.
- term:
id: GO:0005744
label: TIM23 mitochondrial import inner membrane translocase complex
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
- term:
id: GO:0008320
label: protein transmembrane transporter activity
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: Accepted as TIMM23 contribution to TIM23-dependent protein translocation across the mitochondrial inner membrane. TIMM23 is essential in the translocase core, even though recent structural work emphasizes Tim17-family subunits as the dominant translocation cavity.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: '**TIMM23 is essential** within the TIM23 presequence translocase core, but **Tim17-family proteins** appear to provide the dominant **translocation cavity** driven by conserved electrostatics (negative charges).'
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: IEA
original_reference_id: GO_REF:0000044
review:
summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
- term:
id: GO:0005744
label: TIM23 mitochondrial import inner membrane translocase complex
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
- term:
id: GO:0008320
label: protein transmembrane transporter activity
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: Accepted as TIMM23 contribution to TIM23-dependent protein translocation across the mitochondrial inner membrane. TIMM23 is essential in the translocase core, even though recent structural work emphasizes Tim17-family subunits as the dominant translocation cavity.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: '**TIMM23 is essential** within the TIM23 presequence translocase core, but **Tim17-family proteins** appear to provide the dominant **translocation cavity** driven by conserved electrostatics (negative charges).'
- term:
id: GO:0022857
label: transmembrane transporter activity
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: Correct but too broad; the more specific supported function is protein transmembrane transporter activity in the TIM23 presequence translocase.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: Use GO:0008320 protein transmembrane transporter activity and TIM23 complex annotations rather than generic transmembrane transporter activity.
- term:
id: GO:0030150
label: protein import into mitochondrial matrix
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: Correct and core. TIMM23-containing TIM23 translocase imports presequence-containing proteins into the mitochondrial matrix.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: Most mitochondrial proteins are nuclear encoded and must be imported into mitochondria. The **TIM23 complex** (also called the **presequence translocase**) is the major inner-membrane translocase for **presequence-containing precursor proteins**, handling a large fraction of mitochondrial protein biogenesis.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:23260140
review:
summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:23263864
review:
summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:32296183
review:
summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:32814053
review:
summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
- term:
id: GO:0008320
label: protein transmembrane transporter activity
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: Accepted as TIMM23 contribution to TIM23-dependent protein translocation across the mitochondrial inner membrane. TIMM23 is essential in the translocase core, even though recent structural work emphasizes Tim17-family subunits as the dominant translocation cavity.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: '**TIMM23 is essential** within the TIM23 presequence translocase core, but **Tim17-family proteins** appear to provide the dominant **translocation cavity** driven by conserved electrostatics (negative charges).'
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: NAS
original_reference_id: PMID:10339406
review:
summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
- term:
id: GO:0005744
label: TIM23 mitochondrial import inner membrane translocase complex
evidence_type: NAS
original_reference_id: PMID:10339406
review:
summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
- term:
id: GO:0006886
label: intracellular protein transport
evidence_type: NAS
original_reference_id: PMID:10339406
review:
summary: Correct but broad. TIMM23 is specifically involved in mitochondrial protein import via the TIM23 presequence translocase.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: The specific mitochondrial matrix import and TIM23 translocase terms capture the supported biology better than generic intracellular protein transport.
- term:
id: GO:0030150
label: protein import into mitochondrial matrix
evidence_type: TAS
original_reference_id: PMID:10339406
review:
summary: Correct and core. TIMM23-containing TIM23 translocase imports presequence-containing proteins into the mitochondrial matrix.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: Most mitochondrial proteins are nuclear encoded and must be imported into mitochondria. The **TIM23 complex** (also called the **presequence translocase**) is the major inner-membrane translocase for **presequence-containing precursor proteins**, handling a large fraction of mitochondrial protein biogenesis.
- term:
id: GO:0005739
label: mitochondrion
evidence_type: IDA
original_reference_id: GO_REF:0000052
review:
summary: Correct but broad. TIMM23 is specifically localized to the mitochondrial inner membrane and TIM23 complex.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: Prefer mitochondrial inner membrane/TIM23 complex annotations over generic mitochondrion.
- term:
id: GO:0005739
label: mitochondrion
evidence_type: HTP
original_reference_id: PMID:34800366
review:
summary: Correct but broad. TIMM23 is specifically localized to the mitochondrial inner membrane and TIM23 complex.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: Prefer mitochondrial inner membrane/TIM23 complex annotations over generic mitochondrion.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:37160114
review:
summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
- term:
id: GO:0061734
label: type 2 mitophagy
evidence_type: IMP
original_reference_id: PMID:37160114
review:
summary: Supported as a non-core stress-response role. TIMM23 can help PINK1 accumulate during depolarization-linked mitophagy, but its primary function is TIM23 presequence translocase protein import.
action: KEEP_AS_NON_CORE
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: Has a role in the activation of stress-induced mitophagy by protecting PINK1 from OMA1-mediated degradation and facilitating its accumulation at the outer mitochondrial membrane in response to depolarization
- term:
id: GO:0005744
label: TIM23 mitochondrial import inner membrane translocase complex
evidence_type: IDA
original_reference_id: PMID:30598479
review:
summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: IDA
original_reference_id: PMID:25997101
review:
summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: IDA
original_reference_id: PMID:20053669
review:
summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: IDA
original_reference_id: PMID:10339406
review:
summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
- term:
id: GO:0005744
label: TIM23 mitochondrial import inner membrane translocase complex
evidence_type: IDA
original_reference_id: PMID:10339406
review:
summary: Correct. TIMM23 is a core component of the TIM23 mitochondrial inner-membrane presequence translocase complex.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: TAS
original_reference_id: PMID:14726512
review:
summary: Correct. TIMM23 is an integral mitochondrial inner membrane component of the TIM23 translocase.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:15044455
review:
summary: Protein binding is too generic for TIMM23. The informative annotations are TIM23 complex membership, TIMM50/TIMM17/TIMM21/PINK1-related context, and translocase function.
action: MARK_AS_OVER_ANNOTATED
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
reason: Documented interactions should be represented by specific complex or pathway annotations rather than generic protein binding.
- term:
id: GO:0005758
label: mitochondrial intermembrane space
evidence_type: IDA
original_reference_id: PMID:15044455
review:
summary: Supported. TIMM23 has an intermembrane-space-facing region within the inner-membrane TIM23 machinery.
action: ACCEPT
additional_reference_ids:
- file:human/TIMM23/TIMM23-deep-research-falcon.md
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with GO terms
findings: []
- 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: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: GO_REF:0000052
title: Gene Ontology annotation based on curation of immunofluorescence data
findings: []
- id: PMID:10339406
title: Genetic and structural characterization of the human mitochondrial inner membrane translocase.
findings: []
- id: PMID:14726512
title: Organization and function of the small Tim complexes acting along the import pathway of metabolite carriers into mammalian mitochondria.
findings: []
- id: PMID:15044455
title: Tim50, a component of the mitochondrial translocator, regulates mitochondrial integrity and cell death.
findings: []
- id: PMID:20053669
title: Role of Magmas in protein transport and human mitochondria biogenesis.
findings: []
- id: PMID:23260140
title: MITRAC links mitochondrial protein translocation to respiratory-chain assembly and translational regulation.
findings: []
- id: PMID:23263864
title: Methylation-controlled J-protein MCJ acts in the import of proteins into human mitochondria.
findings: []
- id: PMID:25997101
title: QIL1 is a novel mitochondrial protein required for MICOS complex stability and cristae morphology.
findings: []
- id: PMID:30598479
title: ROMO1 is a constituent of the human presequence translocase required for YME1L protease import.
findings: []
- id: PMID:32296183
title: A reference map of the human binary protein interactome.
findings: []
- id: PMID:32814053
title: Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins and Uncovers Widespread Protein Aggregation in Affected Brains.
findings: []
- id: PMID:34800366
title: Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context.
findings: []
- id: PMID:37160114
title: TIM23 facilitates PINK1 activation by safeguarding against OMA1-mediated degradation in damaged mitochondria.
findings: []
- id: file:human/TIMM23/TIMM23-deep-research-falcon.md
title: Falcon deep research report for human TIMM23
findings: []
core_functions:
- description: TIMM23 is a core inner-membrane subunit of the TIM23 presequence translocase, supporting protein translocation into the mitochondrial matrix and sorting/insertion of selected presequence-containing inner-membrane proteins.
supported_by:
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a **core subunit** of the TIM23 inner membrane translocase.
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: Most mitochondrial proteins are nuclear encoded and must be imported into mitochondria. The **TIM23 complex** (also called the **presequence translocase**) is the major inner-membrane translocase for **presequence-containing precursor proteins**, handling a large fraction of mitochondrial protein biogenesis.
- reference_id: file:human/TIMM23/TIMM23-deep-research-falcon.md
supporting_text: TIMM23 is a core subunit of the presequence translocase that, together with TOM and other TIM23 subunits, mediates import of presequence-containing proteins into the matrix and inner membrane.
molecular_function:
id: GO:0008320
label: protein transmembrane transporter activity
directly_involved_in:
- id: GO:0030150
label: protein import into mitochondrial matrix
locations:
- id: GO:0005743
label: mitochondrial inner membrane
- id: GO:0005758
label: mitochondrial intermembrane space
in_complex:
id: GO:0005744
label: TIM23 mitochondrial import inner membrane translocase complex
proposed_new_terms: []
suggested_questions:
- question: Which human TIMM23-containing TIM23 cores differ functionally between TIMM17A and TIMM17B paralog contexts?
experts: []
- question: How separable is TIMM23 structural support of the presequence translocase from its PINK1-linked mitophagy role under depolarizing stress?
experts: []
suggested_experiments:
- hypothesis: TIMM23 contributes primarily as an essential structural/regulatory core subunit while TIMM17-family proteins form the dominant presequence translocation cavity.
description: Use TIMM23 interface mutants in rescue cells and compare TIM23 complex assembly, matrix import substrates, TIM23SORT substrates, and Tim17/TIMM50 interactions by BN-PAGE and in vitro import assays.
- hypothesis: TIMM23-PINK1 interaction during mitochondrial depolarization is a stress-specific function separable from basal TIM23 import.
description: Test TIMM23 mutants that preserve TIM23 complex assembly but disrupt PINK1 association, then measure PINK1 stabilization, PRKN recruitment, and matrix/import substrate flux.