Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0003677 DNA binding	IEA GO_REF:0000043	REMOVE	Summary: HAP4 is annotated with generic DNA binding activity. However, the literature shows HAP4 does not directly bind DNA. The abstract of PMID:2676721 states that in hap4 mutants, "the binding of HAP2 and HAP3 (HAP2/3) is not observed in vitro," and that HAP4 "encodes a regulatory subunit of the bound complex" - not the DNA-binding subunit. PMID:16278450 confirms that "the Hap2p/Hap3p/Hap5p heterotrimer is the DNA-binding component" while "the Hap4p subunit contains the transcriptional activation domain." The IEA annotation appears to be incorrectly transferred from keyword-based mapping. Reason: This annotation is mechanistically incorrect. HAP4 does not directly bind DNA - it provides transcriptional activation domains to the DNA-bound Hap2/3/5 complex. The annotation misrepresents HAP4's function by conflating complex membership with direct DNA binding capability. Supporting Evidence: PMID:2676721 In the hap4 mutant, the binding of HAP2 and HAP3 (HAP2/3) is not observed in vitro. PMID:2676721 The HAP4 gene is regulated transcriptionally by a carbon source, suggesting that it encodes a regulatory subunit of the bound complex. PMID:16278450 The Hap2p/Hap3p/Hap5p heterotrimer is the DNA-binding component of the complex that binds to the consensus 5'-CCAAT-3' sequence in the promoter of target genes. file:yeast/HAP4/HAP4-deep-research-falcon.md model: Edison Scientific Literature
GO:0005634 nucleus	IEA GO_REF:0000120	ACCEPT	Summary: Nuclear localization is appropriate for HAP4, which functions as a transcriptional activator in the nucleus as part of the CCAAT-binding complex at target promoters. Reason: Nuclear localization is correct and consistent with HAP4's role as a transcriptional regulator. This is a core cellular localization feature.
GO:0006351 DNA-templated transcription	IEA GO_REF:0000043	MODIFY	Summary: HAP4 is annotated with DNA-templated transcription, which describes the process of RNA synthesis itself. This is overly generic for a transcriptional regulator. HAP4's specific role is not in performing transcription but in regulating it. Reason: This term describes the core enzymatic process (RNA polymerase activity), not HAP4's function. HAP4 regulates transcription through activation domains, not by performing the transcription reaction. More specific regulatory terms better represent its function. Proposed replacements: positive regulation of transcription by RNA polymerase II Supporting Evidence: PMID:2676721 The sequence of HAP4 shows a highly acidic region, which innactivated the protein when deleted. Replacement of this region with the activation domain of GAL4 restored activity, suggesting that it provides the principal activation domain to the bound HAP2/3/4 complex.
GO:0006355 regulation of DNA-templated transcription	IEA GO_REF:0000002	ACCEPT	Summary: This annotation appropriately captures HAP4's function as a transcriptional regulator through its interaction with the DNA-binding CCAAT-binding factor complex. Reason: This is a mechanistically accurate annotation for a transcriptional regulator/activator. The IEA evidence based on InterPro domain mapping is reasonable for transcription factor domains. Supporting Evidence: PMID:2676721 it provides the principal activation domain to the bound HAP2/3/4 complex
GO:0006109 regulation of carbohydrate metabolic process	NAS PMID:16278450 Assembly of the Hap2p/Hap3p/Hap4p/Hap5p-DNA complex in Sacch...	MARK AS OVER ANNOTATED	Summary: HAP4 is annotated with regulation of carbohydrate metabolism. While HAP4 responds to glucose/carbohydrate availability through glucose-repressible expression, it does not directly regulate carbohydrate metabolic enzymes. Instead, it activates respiratory/mitochondrial genes that oxidize carbohydrates. The annotation conflates metabolic context with direct molecular targets. Reason: HAP4 regulates genes encoding respiratory proteins, not carbohydrate metabolism enzymes. The annotation overstates the scope of HAP4's direct function. GO:0043457 (regulation of cellular respiration) is more accurate. Supporting Evidence: PMID:2676721 The CYC1 gene of Saccharomyces cerevisiae is positively regulated by the HAP2 and HAP3 proteins...and which activate transcription in a nonfermentable carbon source.
GO:0006355 regulation of DNA-templated transcription	NAS PMID:16278450 Assembly of the Hap2p/Hap3p/Hap4p/Hap5p-DNA complex in Sacch...	ACCEPT	Summary: This is a duplicate annotation with different evidence source (NAS vs IEA). Both document HAP4's function as a transcriptional regulator, which strengthens confidence in this core annotation. Reason: Legitimate duplicate with different evidence code. Multiple independent evidence types support this core function annotation. Supporting Evidence: PMID:16278450 The Hap4p subunit contains the transcriptional activation domain necessary for stimulating transcription after interacting with Hap2p/Hap3p/Hap5p.
GO:0043457 regulation of cellular respiration	IMP PMID:2676721 Identification and characterization of HAP4: a third compone...	ACCEPT	Summary: This annotation accurately reflects HAP4's core function identified through the landmark genetic analysis of CYC1, a respiratory gene encoding cytochrome c. HAP4 is shown to be essential for activating respiratory genes in response to nonfermentable carbon sources. Reason: This is mechanistically accurate and represents a core function. The IMP evidence directly supports HAP4's role as a transcriptional activator of respiratory genes. This is among the most informative annotations for HAP4. Supporting Evidence: PMID:2676721 The CYC1 gene of Saccharomyces cerevisiae is positively regulated by the HAP2 and HAP3 proteins, which form a heteromeric complex that binds to a CCAAT box in the upstream activation site, UAS2, and which activate transcription in a nonfermentable carbon source.
GO:0061629 RNA polymerase II-specific DNA-binding transcription factor binding	IDA PMID:11423663 Recruitment of HAT complexes by direct activator interaction...	ACCEPT	Summary: This annotation documents HAP4's protein-protein interactions with coactivator complexes (HAT complexes SAGA and NuA4) through Tra1p binding, which is a key mechanism for its transcriptional activation function. Reason: The IDA evidence correctly documents HAP4's interactions with transcription factor/coactivator complexes. This represents an important molecular mechanism of transcriptional activation. Supporting Evidence: PMID:11423663 acidic activators directly interact with Tra1p, a shared subunit of SAGA and NuA4
GO:0061629 RNA polymerase II-specific DNA-binding transcription factor binding	IPI PMID:11423663 Recruitment of HAT complexes by direct activator interaction...	ACCEPT	Summary: Duplicate annotation with IPI evidence code documenting the same protein interaction. Both IDA and IPI evidence strengthen confidence in HAP4's interaction with transcriptional machinery. Reason: Legitimate duplicate with complementary evidence code. Multiple independent evidence types document this important molecular mechanism. Supporting Evidence: PMID:11423663 acidic activators directly interact with Tra1p, a shared subunit of SAGA and NuA4
GO:0003713 transcription coactivator activity	IMP PMID:2123465 The HAP2 subunit of yeast CCAAT transcriptional activator co...	ACCEPT	Summary: This annotation directly captures HAP4's fundamental function. The source demonstrates through functional analysis that HAP4 provides the primary transcriptional activation domain, and that deletion of the acidic activation region inactivates the protein, while replacement with GAL4 activation domain restores activity. Reason: The IMP evidence directly demonstrates HAP4's coactivator function. This is one of HAP4's most fundamental and well-characterized functions, accurately representing its role as the activating subunit. Supporting Evidence: PMID:2123465 the HAP4 subunit provides the primary transcriptional activation domain
GO:0016602 CCAAT-binding factor complex	IDA PMID:2676721 Identification and characterization of HAP4: a third compone...	ACCEPT	Summary: HAP4 is a bona fide subunit of the CCAAT-binding factor (CBF/HAP) complex, which consists of Hap2, Hap3, Hap4, and Hap5. This annotation correctly reflects complex membership. Reason: This is accurate and represents a fundamental structural feature of HAP4. Complex membership is core information about HAP4's molecular organization. Supporting Evidence: PMID:2676721 a new locus, HAP4, which is shown to encode a subunit of the DNA-binding complex at UAS2
GO:0045944 positive regulation of transcription by RNA polymerase II	IMP PMID:2676721 Identification and characterization of HAP4: a third compone...	ACCEPT	Summary: This annotation captures HAP4's core function as a transcriptional activator. The source demonstrates that HAP4 provides the principal activation domain of the CCAAT-binding complex that activates respiratory genes. Reason: This is a core function annotation with appropriate experimental evidence. HAP4 is a bona fide transcriptional activator of RNA Pol II-transcribed respiratory genes. This represents one of HAP4's most important functions. Supporting Evidence: PMID:2676721 The sequence of HAP4 shows a highly acidic region, which innactivated the protein when deleted. Replacement of this region with the activation domain of GAL4 restored activity, suggesting that it provides the principal activation domain to the bound HAP2/3/4 complex.
GO:0098803 respiratory chain complex	IMP PMID:21108829 cAMP/PKA signaling balances respiratory activity with mitoch...	REMOVE	Summary: HAP4 is annotated as a component of respiratory chain complex. However, HAP4 is a transcription factor that regulates genes encoding respiratory chain components, not a structural component of the respiratory chain itself. The source (PMID:21108829) describes HAP4 as a "transcriptional regulator" involved in "mitochondrial biogenesis," not as a complex component. Reason: This annotation is mechanistically incorrect. HAP4 is a transcription factor that activates genes encoding respiratory chain proteins, not a structural component of respiratory chain complexes (Complexes I-IV in the inner mitochondrial membrane). The annotation conflates transcriptional regulation of respiratory genes with structural participation in respiratory complexes. GO:0043457 (regulation of cellular respiration) is the appropriate annotation. Supporting Evidence: PMID:21108829 the loss of mitochondrial function and production of ROS requires the activity of the transcriptional regulators HAP4, SOK2 and SKO1

Core Functions

Transcriptional activation of respiratory and mitochondrial genes. HAP4 is the primary transcriptional activation subunit of the CCAAT-binding factor complex. It provides multiple acidic activation domains that recruit histone acetyltransferase complexes (SAGA, NuA4) to activate genes encoding respiratory chain components (cytochrome c, ATP synthase subunits, electron transport chain proteins) during the diauxic shift from fermentation to respiration and in response to non-fermentable carbon sources. The activation function is mediated through interaction with Tra1p and other transcriptional machinery.

Molecular Function:

transcription coactivator activity

Supporting Evidence:

PMID:2123465
the HAP4 subunit provides the primary transcriptional activation domain
PMID:2676721
The sequence of HAP4 shows a highly acidic region, which innactivated the protein when deleted. Replacement of this region with the activation domain of GAL4 restored activity, suggesting that it provides the principal activation domain to the bound HAP2/3/4 complex.

Protein-protein interactions with RNA polymerase II transcriptional machinery. HAP4 directly interacts with histone acetyltransferase complexes SAGA and NuA4 through its acidic activation domains binding to the Tra1p subunit. This interaction enables recruitment of chromatin remodeling and histone modification activities to target promoters, facilitating transcriptional activation of respiratory genes.

Molecular Function:

RNA polymerase II-specific DNA-binding transcription factor binding

Supporting Evidence:

PMID:11423663
acidic activators directly interact with Tra1p, a shared subunit of SAGA and NuA4

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:11423663

Recruitment of HAT complexes by direct activator interactions with the ATM-related Tra1 subunit.

PMID:16278450

Assembly of the Hap2p/Hap3p/Hap4p/Hap5p-DNA complex in Saccharomyces cerevisiae.

PMID:21108829

cAMP/PKA signaling balances respiratory activity with mitochondria dependent apoptosis via transcriptional regulation.

PMID:2123465

The HAP2 subunit of yeast CCAAT transcriptional activator contains adjacent domains for subunit association and DNA recognition: model for the HAP2/3/4 complex.

PMID:2676721

Identification and characterization of HAP4: a third component of the CCAAT-bound HAP2/HAP3 heteromer.

file:yeast/HAP4/HAP4-deep-research-falcon.md

Deep research report on HAP4

📚 Additional Documentation

Deep Research Falcon

(HAP4-deep-research-falcon.md)

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organism_full: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast).
protein_family: Not specified in UniProt
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Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: P14064
Protein Description: RecName: Full=Transcriptional activator HAP4;
Gene Information: Name=HAP4; OrderedLocusNames=YKL109W; ORFNames=YKL465;
Organism (full): Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast).
Protein Family: Not specified in UniProt
Key Domains: Hap4_TF_heteromerisation. (IPR018287); Hap4_Hap_bind (PF10297)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "HAP4" matches the protein description above
Verify the organism is correct: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'HAP4' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene HAP4 (gene ID: HAP4, UniProt: P14064) in yeast.

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.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: P14064
Protein Description: RecName: Full=Transcriptional activator HAP4;
Gene Information: Name=HAP4; OrderedLocusNames=YKL109W; ORFNames=YKL465;
Organism (full): Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast).
Protein Family: Not specified in UniProt
Key Domains: Hap4_TF_heteromerisation. (IPR018287); Hap4_Hap_bind (PF10297)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "HAP4" matches the protein description above
Verify the organism is correct: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Please provide a comprehensive research report on the gene HAP4 (gene ID: HAP4, UniProt: P14064) in yeast.

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.

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.

Research Plan and Methodology
We verified gene/protein identity before synthesis. HAP4 (UniProt P14064) in Saccharomyces cerevisiae S288c encodes the transcriptional activation subunit of the Hap2/3/4/5 CCAAT-binding complex, which activates respiratory and mitochondrial gene programs during the diauxic shift. We prioritized 2023–2024 peer‑reviewed and expert sources, supplemented by high‑quality preprints where they provide unique, recent insights. (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10, henriques2023multiomicdataand pages 5-7, wang2024metabolicregulationof pages 17-19)

1) Key concepts and definitions with current understanding
- Identity and complex membership: Hap4 is the activation subunit of the HAP (Hap2/3/4/5) CCAAT-binding transcription complex in budding yeast. Hap2/3/5 mediate DNA binding to CCAAT motifs, while Hap4 provides the activation domain; all are required for full activation of respiratory genes. (henriques2023multiomicdataand pages 1-5, wang2024metabolicregulationof pages 17-19)
- Core biological role: The HAP complex is a central regulator of the shift from fermentation to respiration, coordinating transcription of mitochondrial/respiratory genes (e.g., cytochrome c, ATP synthase components) during the diauxic shift and ethanol utilization. (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10)
- Localization and domains: Hap4 functions in the nucleus as a transcriptional activator associated with the CCAAT-bound Hap2/3/5 complex. Recent sources reaffirm its role as the activation subunit; while PF10297 (Hap4_Hap_bind) is the known Hap4–Hap complex interaction domain from databases, recent 2023–2024 literature summarized here focuses on complex function and signaling integration rather than detailed domain mapping. (wang2024metabolicregulationof pages 17-19)

2) Recent developments and latest research (2023–2024)
- Signal integration model: A 2023 systems study integrating proteomics and transcriptomics proposes that the HAP complex integrates SNF1 (AMPK-like) signaling, which induces HAP4 at low glucose, with PKA/TORC1 signaling, which regulates HAP5 and ribosomal programs. The model reproduces diauxic-shift dynamics with high accuracy (R2 ≈ 0.96–0.98), predicts Hap5 upregulation (~2.5-fold) as glucose falls, and supports a revised view where both Hap4 and Hap5 are dynamically regulated. URL: https://doi.org/10.21203/rs.3.rs-3438615/v1 (posted Oct 2023). (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10, henriques2023multiomicdataand pages 5-7, henriques2023multiomicdataand pages 13-15)
- SNF1/AMPK and mitochondrial proteostasis context: A 2024 study on metabolic regulation of misfolded protein import into mitochondria (MAGIC pathway) highlights SNF1’s role in mitochondrial biogenesis and references Hap4 as the activation subunit of the CCAAT-bound HAP2/3 complex that promotes respiratory gene expression during nutrient shifts. URL: https://doi.org/10.1101/2023.03.29.534670 (posted Mar 2024). (wang2024metabolicregulationof pages 17-19)
- Promoter crosstalk around HAP4: A 2024 Nucleic Acids Research article on zinc‑cluster regulators of the fermentation-to-respiration transition reports cooperative DNA-binding behavior among regulators, including interactions at the HAP4 promoter with Rds2/Ert1, pointing to network-level control shaping HAP4 expression in glucose withdrawal. URL: https://doi.org/10.1093/nar/gkad1185 (Dec 2024). (henriques2023multiomicdataand pages 13-15)
- Aging and heme signaling: A 2024 GeroScience paper shows heme supplementation extends replicative lifespan independently of Hap4 and paradoxically reduces Hap4 protein levels (p<0.001), with MG132 proteasome inhibition failing to reverse this decrease, suggesting non‑proteasomal regulation. URL: https://doi.org/10.1007/s11357-024-01218-9 (May 2024). (patnaik2024lifespanregulationby pages 4-7)

3) Current applications and real-world implementations
- Stress and inhibitor tolerance in lignocellulosic fermentation: Overexpression of HAP4 improved fermentation performance under combined acetic and formic acid stress during glucose–xylose co-fermentation; transcriptomics implicated upregulation of transport and ribosome biogenesis genes and genome‑stability factors, suggesting multiple tolerance mechanisms. URL: https://doi.org/10.1186/s12934-025-02764-3 (Jul 2025). Although 2025, it provides the most recent applied dataset. (xiao2025regulatorymechanismof pages 1-2, xiao2025regulatorymechanismof pages 8-10)
- Systems and mitochondrial fitness: Work linking SNF1 activation, Hap4 function, and mitochondrial biogenesis provides rationale for using HAP4 activation to bias respiration in engineered strains, including contexts involving proteostasis and metabolic stress. URL: https://doi.org/10.1101/2023.03.29.534670 (Mar 2024). (wang2024metabolicregulationof pages 17-19)
- Industrial/synthetic biology implications: Modeling indicates HAP complex activity responds to glucose and nutrient-signaling axes; leveraging this can tune respiratory capacity and timing of the diauxic shift for bioproduction processes where respiratory metabolism enhances yield or product quality. URL: https://doi.org/10.21203/rs.3.rs-3438615/v1 (Oct 2023). (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10, henriques2023multiomicdataand pages 5-7)

4) Expert opinions and analysis from authoritative sources
- The 2023 integrated model reframes HAP complex regulation as jointly controlled by SNF1 (inducing Hap4) and PKA/TORC1 (upregulating Hap5 under low glucose), supporting an “integrator” role of the HAP complex across nutrient-sensing pathways. This helps explain variable outcomes of HAP4 overexpression across studies and suggests combinatorial modulation (e.g., of TORC1/PKA) may be necessary to fully activate respiratory programs. (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10, henriques2023multiomicdataand pages 13-15)
- The 2024 NAR study underscores promoter-level crosstalk at HAP4 with other regulators of the fermentative–respiratory switch, highlighting that HAP4 expression is embedded within a broader transcription factor network (Rds2/Ert1), not a simple on/off switch. (henriques2023multiomicdataand pages 13-15)
- Aging work decoupling heme-driven lifespan extension from Hap4 indicates that while Hap4 is a major driver of respiratory gene expression and has been linked to lifespan extension, upstream metabolic signals (heme) can bypass Hap4, pointing to parallel longevity pathways and cautioning against assuming Hap4 dependence in all respiration-linked phenotypes. (patnaik2024lifespanregulationby pages 4-7)

5) Relevant statistics and data from recent studies
- Model fit and regulatory magnitudes: The multi‑omic dynamic model reproduces diauxic-shift transitions with R2 ≈ 0.96 (DM2015) and 0.98 (DD2020). It infers Hap5 upregulation by ≈2.5-fold as glucose decreases and indicates HAP4 transcriptional response is ~10× stronger than HAP5 in a validation benchmark referencing classic data. URL: https://doi.org/10.21203/rs.3.rs-3438615/v1 (Oct 2023). (henriques2023multiomicdataand pages 7-10, henriques2023multiomicdataand pages 5-7)
- Heme and Hap4 protein abundance: Heme supplementation significantly reduces Hap4 protein (p<0.001) without rescue by proteasome inhibitor MG132, despite replicative lifespan extension occurring independently of Hap4. URL: https://doi.org/10.1007/s11357-024-01218-9 (May 2024). (patnaik2024lifespanregulationby pages 4-7)
- Mixed-acid stress application: Under co‑fermentation with acetic+formic acid, HAP4 overexpression correlates with upregulation of LEU1, ALD6, NCE103, PDR5, STL1, and PHO89, implicating TOR activation, NADPH generation, pH homeostasis, xenobiotic efflux, and glycerol uptake; these transcriptomic adjustments align with improved inhibitor tolerance and fermentation performance. URL: https://doi.org/10.1186/s12934-025-02764-3 (Jul 2025). (xiao2025regulatorymechanismof pages 8-10, xiao2025regulatorymechanismof pages 1-2)

Functional summary and localization
- Functional role: Hap4 is the activation subunit of the CCAAT-binding HAP complex that drives expression of respiratory/mitochondrial genes in response to nutrient conditions; it is induced under low glucose via SNF1 and works with Hap2/3/5 to promote oxidative metabolism during diauxic shift. (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10, wang2024metabolicregulationof pages 17-19)
- Localization: Operates in the nucleus as part of a transcriptional activator complex binding CCAAT motifs in target promoters, consistent with promoter‑centric regulation of respiratory gene programs and promoter-level regulation at the HAP4 locus itself. (henriques2023multiomicdataand pages 13-15, wang2024metabolicregulationof pages 17-19)
- Pathway context: Integrates signals from SNF1/AMPK and PKA/TORC1, with SNF1 upregulating HAP4 and PKA/TORC1 controlling HAP5 and ribosomal programs; together they coordinate the transcriptional reprogramming from fermentation to respiration. (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10, henriques2023multiomicdataand pages 13-15)

Notes on domain annotation
- The Hap4_Hap_bind (PF10297) interaction domain is consistent with Hap4’s role as activation subunit associating with the DNA‑binding Hap2/3/5 complex, but recent 2023–2024 sources cited here focus on regulatory integration rather than structural domain mapping. Where specific domain claims are required, consult curated databases in parallel with primary literature. (wang2024metabolicregulationof pages 17-19)

Caveats and open questions
- Overexpression of HAP4 alone can increase respiratory capacity but may be insufficient to fully derepress all respiratory targets without concurrent modulation of PKA/TORC1 signaling—consistent with model predictions that the complex integrates multiple nutrient‑sensing inputs. (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10)
- Heme’s reduction of Hap4 protein yet Hap4‑independent lifespan extension argues for parallel or downstream pathways affecting mitochondrial function and longevity that do not require Hap4, warranting further mechanistic dissection. (patnaik2024lifespanregulationby pages 4-7)

URLs and dates (selection)
- Henriques et al., Research Square, posted Oct 2023: https://doi.org/10.21203/rs.3.rs-3438615/v1 (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10, henriques2023multiomicdataand pages 5-7, henriques2023multiomicdataand pages 13-15)
- Wang et al., bioRxiv, posted Mar 2024: https://doi.org/10.1101/2023.03.29.534670 (wang2024metabolicregulationof pages 17-19)
- Martinez et al., Nucleic Acids Research, Dec 2024: https://doi.org/10.1093/nar/gkad1185 (henriques2023multiomicdataand pages 13-15)
- Patnaik et al., GeroScience, May 2024: https://doi.org/10.1007/s11357-024-01218-9 (patnaik2024lifespanregulationby pages 4-7)
- Xiao et al., Microbial Cell Factories, Jul 2025: https://doi.org/10.1186/s12934-025-02764-3 (xiao2025regulatorymechanismof pages 1-2, xiao2025regulatorymechanismof pages 8-10)

Conclusion
Hap4 (P14064) is the transcriptional activation subunit of the HAP CCAAT-binding complex that orchestrates the transition to respiratory metabolism by activating mitochondrial and respiratory gene expression during the diauxic shift. Recent systems work reframes HAP complex regulation as an integration point for SNF1/AMPK and PKA/TORC1, with evidence that HAP5 is dynamically regulated downstream of PKA/TORC1 while Hap4 is induced by SNF1 under low glucose. Applications span stress‑tolerant fermentation and potential lifespan modulation, though heme-driven longevity can occur independently of Hap4. Overall, HAP4’s nuclear activation role and pathway integration make it a key lever for engineering yeast respiratory metabolism and stress performance. (henriques2023multiomicdataand pages 1-5, henriques2023multiomicdataand pages 7-10, henriques2023multiomicdataand pages 5-7, henriques2023multiomicdataand pages 13-15, wang2024metabolicregulationof pages 17-19, xiao2025regulatorymechanismof pages 1-2, patnaik2024lifespanregulationby pages 4-7, xiao2025regulatorymechanismof pages 8-10)

References

(henriques2023multiomicdataand pages 1-5): David Henriques, Artai Moimenta, and Eva Balsa-Canto. Multi-omic data and modelling analyses reveal that hap complex integrates torc1/pka and snf1 signalling pathways. Oct 2023. URL: https://doi.org/10.21203/rs.3.rs-3438615/v1, doi:10.21203/rs.3.rs-3438615/v1.
(henriques2023multiomicdataand pages 7-10): David Henriques, Artai Moimenta, and Eva Balsa-Canto. Multi-omic data and modelling analyses reveal that hap complex integrates torc1/pka and snf1 signalling pathways. Oct 2023. URL: https://doi.org/10.21203/rs.3.rs-3438615/v1, doi:10.21203/rs.3.rs-3438615/v1.
(henriques2023multiomicdataand pages 5-7): David Henriques, Artai Moimenta, and Eva Balsa-Canto. Multi-omic data and modelling analyses reveal that hap complex integrates torc1/pka and snf1 signalling pathways. Oct 2023. URL: https://doi.org/10.21203/rs.3.rs-3438615/v1, doi:10.21203/rs.3.rs-3438615/v1.
(wang2024metabolicregulationof pages 17-19): Yuhao Wang, Linhao Ruan, Jin Zhu, Xi Zhang, Alexander Chih-Chieh Chang, Alexis Tomaszewski, and Rong Li. Metabolic regulation of misfolded protein import into mitochondria. bioRxiv, Mar 2024. URL: https://doi.org/10.1101/2023.03.29.534670, doi:10.1101/2023.03.29.534670. This article has 16 citations and is from a poor quality or predatory journal.
(henriques2023multiomicdataand pages 13-15): David Henriques, Artai Moimenta, and Eva Balsa-Canto. Multi-omic data and modelling analyses reveal that hap complex integrates torc1/pka and snf1 signalling pathways. Oct 2023. URL: https://doi.org/10.21203/rs.3.rs-3438615/v1, doi:10.21203/rs.3.rs-3438615/v1.
(patnaik2024lifespanregulationby pages 4-7): Praveen K. Patnaik, Nour Nady, Hanna Barlit, Ali Gülhan, and Vyacheslav M. Labunskyy. Lifespan regulation by targeting heme signaling in yeast. GeroScience, 46:5235-5245, May 2024. URL: https://doi.org/10.1007/s11357-024-01218-9, doi:10.1007/s11357-024-01218-9. This article has 0 citations and is from a peer-reviewed journal.
(xiao2025regulatorymechanismof pages 1-2): Xin-Yu Xiao, Bo Li, Zi-Yuan Xia, Quan Zhang, Cai-Yun Xie, and Yue-Qin Tang. Regulatory mechanism of haa1p and hap4p in saccharomyces cerevisiae to mixed acetic acid and formic acid when fermenting mixed glucose and xylose. Microbial Cell Factories, Jul 2025. URL: https://doi.org/10.1186/s12934-025-02764-3, doi:10.1186/s12934-025-02764-3. This article has 2 citations and is from a peer-reviewed journal.
(xiao2025regulatorymechanismof pages 8-10): Xin-Yu Xiao, Bo Li, Zi-Yuan Xia, Quan Zhang, Cai-Yun Xie, and Yue-Qin Tang. Regulatory mechanism of haa1p and hap4p in saccharomyces cerevisiae to mixed acetic acid and formic acid when fermenting mixed glucose and xylose. Microbial Cell Factories, Jul 2025. URL: https://doi.org/10.1186/s12934-025-02764-3, doi:10.1186/s12934-025-02764-3. This article has 2 citations and is from a peer-reviewed journal.

Citations

wang2024metabolicregulationof pages 17-19
henriques2023multiomicdataand pages 13-15
patnaik2024lifespanregulationby pages 4-7
henriques2023multiomicdataand pages 1-5
henriques2023multiomicdataand pages 7-10
henriques2023multiomicdataand pages 5-7
xiao2025regulatorymechanismof pages 1-2
xiao2025regulatorymechanismof pages 8-10
https://doi.org/10.21203/rs.3.rs-3438615/v1
https://doi.org/10.1101/2023.03.29.534670
https://doi.org/10.1093/nar/gkad1185
https://doi.org/10.1007/s11357-024-01218-9
https://doi.org/10.1186/s12934-025-02764-3
https://doi.org/10.21203/rs.3.rs-3438615/v1,
https://doi.org/10.1101/2023.03.29.534670,
https://doi.org/10.1007/s11357-024-01218-9,
https://doi.org/10.1186/s12934-025-02764-3,

📄 View Raw YAML

id: P14064
gene_symbol: HAP4
aliases:
  - YKL109W
  - YKL465
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:559292
  label: Saccharomyces cerevisiae
description: |-
  HAP4 (Heme activator protein 4) is the transcriptional activation subunit of the CCAAT-binding factor (CBF/HAP complex), a heterotetrameric transcription factor (Hap2/3/4/5). HAP4 does not bind DNA directly but associates with the DNA-binding Hap2/3/5 heterotrimer and provides the primary transcriptional activation domains necessary for stimulating gene expression. The HAP complex regulates the diauxic shift from fermentation to respiration by activating transcription of genes encoding mitochondrial proteins and electron transport chain components in response to nutrient depletion (low glucose). HAP4 expression is induced by SNF1/AMPK signaling under low glucose conditions and is glucose-repressible. Core functions include transcriptional activation of respiratory metabolism genes and metabolic adaptation to nutrient availability.
existing_annotations:
  - term:
      id: GO:0003677
      label: DNA binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: |-
        HAP4 is annotated with generic DNA binding activity. However, the literature shows HAP4 does not directly bind DNA. The abstract of PMID:2676721 states that in hap4 mutants, "the binding of HAP2 and HAP3 (HAP2/3) is not observed in vitro," and that HAP4 "encodes a regulatory subunit of the bound complex" - not the DNA-binding subunit. PMID:16278450 confirms that "the Hap2p/Hap3p/Hap5p heterotrimer is the DNA-binding component" while "the Hap4p subunit contains the transcriptional activation domain." The IEA annotation appears to be incorrectly transferred from keyword-based mapping.
      action: REMOVE
      reason: |-
        This annotation is mechanistically incorrect. HAP4 does not directly bind DNA - it provides transcriptional activation domains to the DNA-bound Hap2/3/5 complex. The annotation misrepresents HAP4's function by conflating complex membership with direct DNA binding capability.
      additional_reference_ids:
        - PMID:16278450
      supported_by:
        - reference_id: PMID:2676721
          supporting_text: "In the hap4 mutant, the binding of HAP2 and HAP3 (HAP2/3)
            is not observed in vitro."
        - reference_id: PMID:2676721
          supporting_text: "The HAP4 gene is regulated transcriptionally by a carbon
            source, suggesting that it encodes a regulatory subunit of the bound complex."
        - reference_id: PMID:16278450
          supporting_text: "The Hap2p/Hap3p/Hap5p heterotrimer is the DNA-binding
            component of the complex that binds to the consensus 5'-CCAAT-3' sequence
            in the promoter of target genes."

        - reference_id: file:yeast/HAP4/HAP4-deep-research-falcon.md
          supporting_text: 'model: Edison Scientific Literature'
  - term:
      id: GO:0005634
      label: nucleus
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: |-
        Nuclear localization is appropriate for HAP4, which functions as a transcriptional activator in the nucleus as part of the CCAAT-binding complex at target promoters.
      action: ACCEPT
      reason: |-
        Nuclear localization is correct and consistent with HAP4's role as a transcriptional regulator. This is a core cellular localization feature.

  - term:
      id: GO:0006351
      label: DNA-templated transcription
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: |-
        HAP4 is annotated with DNA-templated transcription, which describes the process of RNA synthesis itself. This is overly generic for a transcriptional regulator. HAP4's specific role is not in performing transcription but in regulating it.
      action: MODIFY
      reason: |-
        This term describes the core enzymatic process (RNA polymerase activity), not HAP4's function. HAP4 regulates transcription through activation domains, not by performing the transcription reaction. More specific regulatory terms better represent its function.
      proposed_replacement_terms:
        - id: GO:0045944
          label: positive regulation of transcription by RNA polymerase II
      supported_by:
        - reference_id: PMID:2676721
          supporting_text: "The sequence of HAP4 shows a highly acidic region, which
            innactivated the protein when deleted. Replacement of this region with
            the activation domain of GAL4 restored activity, suggesting that it provides
            the principal activation domain to the bound HAP2/3/4 complex."

  - term:
      id: GO:0006355
      label: regulation of DNA-templated transcription
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    review:
      summary: |-
        This annotation appropriately captures HAP4's function as a transcriptional regulator through its interaction with the DNA-binding CCAAT-binding factor complex.
      action: ACCEPT
      reason: |-
        This is a mechanistically accurate annotation for a transcriptional regulator/activator. The IEA evidence based on InterPro domain mapping is reasonable for transcription factor domains.
      supported_by:
        - reference_id: PMID:2676721
          supporting_text: "it provides the principal activation domain to the bound
            HAP2/3/4 complex"

  - term:
      id: GO:0006109
      label: regulation of carbohydrate metabolic process
    evidence_type: NAS
    original_reference_id: PMID:16278450
    review:
      summary: |-
        HAP4 is annotated with regulation of carbohydrate metabolism. While HAP4 responds to glucose/carbohydrate availability through glucose-repressible expression, it does not directly regulate carbohydrate metabolic enzymes. Instead, it activates respiratory/mitochondrial genes that oxidize carbohydrates. The annotation conflates metabolic context with direct molecular targets.
      action: MARK_AS_OVER_ANNOTATED
      reason: |-
        HAP4 regulates genes encoding respiratory proteins, not carbohydrate metabolism enzymes. The annotation overstates the scope of HAP4's direct function. GO:0043457 (regulation of cellular respiration) is more accurate.
      supported_by:
        - reference_id: PMID:2676721
          supporting_text: "The CYC1 gene of Saccharomyces cerevisiae is positively
            regulated by the HAP2 and HAP3 proteins...and which activate transcription
            in a nonfermentable carbon source."

  - term:
      id: GO:0006355
      label: regulation of DNA-templated transcription
    evidence_type: NAS
    original_reference_id: PMID:16278450
    review:
      summary: |-
        This is a duplicate annotation with different evidence source (NAS vs IEA). Both document HAP4's function as a transcriptional regulator, which strengthens confidence in this core annotation.
      action: ACCEPT
      reason: |-
        Legitimate duplicate with different evidence code. Multiple independent evidence types support this core function annotation.
      supported_by:
        - reference_id: PMID:16278450
          supporting_text: "The Hap4p subunit contains the transcriptional activation
            domain necessary for stimulating transcription after interacting with
            Hap2p/Hap3p/Hap5p."

  - term:
      id: GO:0043457
      label: regulation of cellular respiration
    evidence_type: IMP
    original_reference_id: PMID:2676721
    review:
      summary: |-
        This annotation accurately reflects HAP4's core function identified through the landmark genetic analysis of CYC1, a respiratory gene encoding cytochrome c. HAP4 is shown to be essential for activating respiratory genes in response to nonfermentable carbon sources.
      action: ACCEPT
      reason: |-
        This is mechanistically accurate and represents a core function. The IMP evidence directly supports HAP4's role as a transcriptional activator of respiratory genes. This is among the most informative annotations for HAP4.
      supported_by:
        - reference_id: PMID:2676721
          supporting_text: "The CYC1 gene of Saccharomyces cerevisiae is positively
            regulated by the HAP2 and HAP3 proteins, which form a heteromeric complex
            that binds to a CCAAT box in the upstream activation site, UAS2, and which
            activate transcription in a nonfermentable carbon source."

  - term:
      id: GO:0061629
      label: RNA polymerase II-specific DNA-binding transcription factor binding
    evidence_type: IDA
    original_reference_id: PMID:11423663
    review:
      summary: |-
        This annotation documents HAP4's protein-protein interactions with coactivator complexes (HAT complexes SAGA and NuA4) through Tra1p binding, which is a key mechanism for its transcriptional activation function.
      action: ACCEPT
      reason: |-
        The IDA evidence correctly documents HAP4's interactions with transcription factor/coactivator complexes. This represents an important molecular mechanism of transcriptional activation.
      supported_by:
        - reference_id: PMID:11423663
          supporting_text: "acidic activators directly interact with Tra1p, a shared
            subunit of SAGA and NuA4"

  - term:
      id: GO:0061629
      label: RNA polymerase II-specific DNA-binding transcription factor binding
    evidence_type: IPI
    original_reference_id: PMID:11423663
    review:
      summary: |-
        Duplicate annotation with IPI evidence code documenting the same protein interaction. Both IDA and IPI evidence strengthen confidence in HAP4's interaction with transcriptional machinery.
      action: ACCEPT
      reason: |-
        Legitimate duplicate with complementary evidence code. Multiple independent evidence types document this important molecular mechanism.
      supported_by:
        - reference_id: PMID:11423663
          supporting_text: "acidic activators directly interact with Tra1p, a shared
            subunit of SAGA and NuA4"

  - term:
      id: GO:0003713
      label: transcription coactivator activity
    evidence_type: IMP
    original_reference_id: PMID:2123465
    review:
      summary: |-
        This annotation directly captures HAP4's fundamental function. The source demonstrates through functional analysis that HAP4 provides the primary transcriptional activation domain, and that deletion of the acidic activation region inactivates the protein, while replacement with GAL4 activation domain restores activity.
      action: ACCEPT
      reason: |-
        The IMP evidence directly demonstrates HAP4's coactivator function. This is one of HAP4's most fundamental and well-characterized functions, accurately representing its role as the activating subunit.
      supported_by:
        - reference_id: PMID:2123465
          supporting_text: "the HAP4 subunit provides the primary transcriptional
            activation domain"

  - term:
      id: GO:0016602
      label: CCAAT-binding factor complex
    evidence_type: IDA
    original_reference_id: PMID:2676721
    review:
      summary: |-
        HAP4 is a bona fide subunit of the CCAAT-binding factor (CBF/HAP) complex, which consists of Hap2, Hap3, Hap4, and Hap5. This annotation correctly reflects complex membership.
      action: ACCEPT
      reason: |-
        This is accurate and represents a fundamental structural feature of HAP4. Complex membership is core information about HAP4's molecular organization.
      supported_by:
        - reference_id: PMID:2676721
          supporting_text: "a new locus, HAP4, which is shown to encode a subunit
            of the DNA-binding complex at UAS2"

  - term:
      id: GO:0045944
      label: positive regulation of transcription by RNA polymerase II
    evidence_type: IMP
    original_reference_id: PMID:2676721
    review:
      summary: |-
        This annotation captures HAP4's core function as a transcriptional activator. The source demonstrates that HAP4 provides the principal activation domain of the CCAAT-binding complex that activates respiratory genes.
      action: ACCEPT
      reason: |-
        This is a core function annotation with appropriate experimental evidence. HAP4 is a bona fide transcriptional activator of RNA Pol II-transcribed respiratory genes. This represents one of HAP4's most important functions.
      supported_by:
        - reference_id: PMID:2676721
          supporting_text: "The sequence of HAP4 shows a highly acidic region, which
            innactivated the protein when deleted. Replacement of this region with
            the activation domain of GAL4 restored activity, suggesting that it provides
            the principal activation domain to the bound HAP2/3/4 complex."

  - term:
      id: GO:0098803
      label: respiratory chain complex
    evidence_type: IMP
    original_reference_id: PMID:21108829
    review:
      summary: |-
        HAP4 is annotated as a component of respiratory chain complex. However, HAP4 is a transcription factor that regulates genes encoding respiratory chain components, not a structural component of the respiratory chain itself. The source (PMID:21108829) describes HAP4 as a "transcriptional regulator" involved in "mitochondrial biogenesis," not as a complex component.
      action: REMOVE
      reason: |-
        This annotation is mechanistically incorrect. HAP4 is a transcription factor that activates genes encoding respiratory chain proteins, not a structural component of respiratory chain complexes (Complexes I-IV in the inner mitochondrial membrane). The annotation conflates transcriptional regulation of respiratory genes with structural participation in respiratory complexes. GO:0043457 (regulation of cellular respiration) is the appropriate annotation.
      additional_reference_ids:
        - PMID:21108829
      supported_by:
        - reference_id: PMID:21108829
          supporting_text: "the loss of mitochondrial function and production of ROS
            requires the activity of the transcriptional regulators HAP4, SOK2 and
            SKO1"

references:
  - id: GO_REF:0000002
    title: Gene Ontology annotation through association of InterPro records with
      GO terms
  - id: GO_REF:0000043
    title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword 
      mapping
  - id: GO_REF:0000120
    title: Combined Automated Annotation using Multiple IEA Methods
  - id: PMID:11423663
    title: Recruitment of HAT complexes by direct activator interactions with 
      the ATM-related Tra1 subunit.
  - id: PMID:16278450
    title: Assembly of the Hap2p/Hap3p/Hap4p/Hap5p-DNA complex in Saccharomyces 
      cerevisiae.
  - id: PMID:21108829
    title: cAMP/PKA signaling balances respiratory activity with mitochondria 
      dependent apoptosis via transcriptional regulation.
  - id: PMID:2123465
    title: 'The HAP2 subunit of yeast CCAAT transcriptional activator contains adjacent
      domains for subunit association and DNA recognition: model for the HAP2/3/4
      complex.'
  - id: PMID:2676721
    title: 'Identification and characterization of HAP4: a third component of the
      CCAAT-bound HAP2/HAP3 heteromer.'

  - id: file:yeast/HAP4/HAP4-deep-research-falcon.md
    title: Deep research report on HAP4
    findings: []
core_functions:
  - description: |-
      Transcriptional activation of respiratory and mitochondrial genes. HAP4 is the primary transcriptional activation subunit of the CCAAT-binding factor complex. It provides multiple acidic activation domains that recruit histone acetyltransferase complexes (SAGA, NuA4) to activate genes encoding respiratory chain components (cytochrome c, ATP synthase subunits, electron transport chain proteins) during the diauxic shift from fermentation to respiration and in response to non-fermentable carbon sources. The activation function is mediated through interaction with Tra1p and other transcriptional machinery.
    molecular_function:
      id: GO:0003713
      label: transcription coactivator activity
    supported_by:
      - reference_id: PMID:2123465
        supporting_text: "the HAP4 subunit provides the primary transcriptional activation
          domain"
      - reference_id: PMID:2676721
        supporting_text: "The sequence of HAP4 shows a highly acidic region, which
          innactivated the protein when deleted. Replacement of this region with the
          activation domain of GAL4 restored activity, suggesting that it provides
          the principal activation domain to the bound HAP2/3/4 complex."

  - description: |-
      Protein-protein interactions with RNA polymerase II transcriptional machinery. HAP4 directly interacts with histone acetyltransferase complexes SAGA and NuA4 through its acidic activation domains binding to the Tra1p subunit. This interaction enables recruitment of chromatin remodeling and histone modification activities to target promoters, facilitating transcriptional activation of respiratory genes.
    molecular_function:
      id: GO:0061629
      label: RNA polymerase II-specific DNA-binding transcription factor binding
    supported_by:
      - reference_id: PMID:11423663
        supporting_text: "acidic activators directly interact with Tra1p, a shared
          subunit of SAGA and NuA4"

HAP4

Gene Description

Existing Annotations Review

Core Functions

References

📚 Additional Documentation

Deep Research Falcon

Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Output

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Citations

📄 View Raw YAML