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this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.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.
NCU08110 is not an ambiguous human or bacterial gene symbol in the material retrieved. The supplied UniProt record assigns Q7SCX0 to ORF NCU08110 in Neurospora crassa strain ATCC 24698/74-OR23-1A and describes the product as a VTC4-family vacuolar transporter chaperone subunit and polyphosphate polymerase. Exact searches for “NCU08110” and “Q7SCX0” found no conflicting gene identity, but also no publication directly characterizing this particular protein. Consequently, its detailed annotation rests on the supplied UniProt/InterPro record and experimentally established properties of fungal Vtc4 orthologs—not on direct NCU08110 biochemical or cell-biological experiments.
The most defensible primary-function assignment is therefore: NCU08110 encodes the putative catalytic Vtc4 subunit of a vacuolar membrane polyphosphate-polymerase/translocase complex. It is expected to use cytosolic ATP—more generally, experimentally studied Vtc4 can accept an NTP—to extend an inorganic phosphate/polyphosphate primer in a Mn²⁺-dependent reaction, while the VTC complex simultaneously moves the growing polyphosphate chain into the vacuolar lumen. Its SPX domain likely couples activity to cellular phosphate status through inositol-pyrophosphate signaling. The predicted physiological role is vacuolar phosphate storage and buffering rather than ordinary solute transport.
| Claim or feature | Best-supported interpretation | Evidence basis | Confidence | Key caveat |
|---|---|---|---|---|
| Identity | Q7SCX0 corresponds to ORF NCU08110 in Neurospora crassa strain 74-OR23-1A and is annotated as a VTC4-family protein. | Supplied UniProt annotation; exact-symbol and accession searches found no conflicting identity. | High for database identity | No target-specific publication independently validating the assignment was found. |
| Domain architecture | The protein contains an N-terminal SPX phosphate-signaling domain, a catalytic VTC or triphosphate-tunnel-metalloenzyme-like region, and a C-terminal membrane-associated VTC module. Reported terms include DUF202, SPX_dom, VTC_domain, VTC_sf, and VTC_Complex_Subunit. Comparable fungal Vtc4 proteins have cytoplasm-facing SPX and polymerase regions plus a membrane anchor. | Supplied UniProt and InterPro annotations; architecture supported by experimentally studied fungal Vtc4 orthologs (schwer2022cleavagepolyadenylationfactorcft1 pages 15-17, schwer2022cleavagepolyadenylationfactorcft1 pages 12-15). | High for annotated domains; moderate to high for topology | Domain presence does not prove orientation, catalytic competence, or membrane topology in N. crassa. |
| Catalytic reaction and substrate | Most likely catalyzes Mn²⁺-dependent transfer of the terminal phosphate of a nucleoside triphosphate, physiologically ATP, to a phosphate or polyphosphate-chain terminus, extending inorganic polyphosphate and producing ADP. | UniProt assigns polyphosphate kinase activity and EC 2.7.4.1; fungal Vtc4 experiments establish manganese-dependent transfer of an NTP γ-phosphate and identify ATP-binding residues (schwer2022cleavagepolyadenylationfactorcft1 pages 15-17, schwer2022cleavagepolyadenylationfactorcft1 pages 12-15). | High for VTC4-family chemistry; moderate for NCU08110 specifically | ATP exclusivity, kinetic constants, primer preference, metal specificity, and purified NCU08110 activity have not been measured directly. |
| Localization | Predicted to be an integral component of the vacuolar membrane, with catalytic and SPX regions exposed to the cytosol and polyphosphate delivered into the vacuolar lumen. | Functional name and membrane-associated VTC domains in the supplied annotation; vacuolar-membrane localization demonstrated for yeast Vtc4 complexes (gerasimaite2017inositolpyrophosphatespecificity pages 16-20, bentleydesousa2021vtc5islocalized pages 1-2). | Moderate to high | No microscopy, fractionation, or topology experiment for NCU08110 was found. |
| Complex role and translocation | Likely serves as the catalytic subunit of a multisubunit VTC complex that couples ATP-dependent polyphosphate polymerization directly to translocation through a membrane channel into the vacuole. Yeast complexes contain Vtc4, Vtc1, and Vtc2 or Vtc3; structural work summarized for fungi reports a 3:1:1 Vtc4:Vtc3:Vtc1 assembly with 15 transmembrane helices. | Ortholog experiments and structural synthesis (tan2025multilayeredregulationof pages 8-10, schwer2022cleavagepolyadenylationfactorcft1 pages 12-15, bentleydesousa2021vtc5islocalized pages 1-2). | High for the fungal VTC mechanism; moderate for the exact N. crassa composition | The identities, stoichiometry, and physical interactions of NCU08110-containing complexes remain untested. |
| SPX regulation | The N-terminal SPX domain probably senses inositol pyrophosphates and activates or relieves inhibition of polyphosphate synthesis when cellular phosphate is abundant. In budding yeast, 5-PP-InsP₅ stimulates VTC near 0.5 µM; 1,5-(PP)₂-InsP₄ is more potent in vitro, and VTC activity can increase about 20-fold. | Fungal-ortholog biochemical and genetic experiments (gerasimaite2017inositolpyrophosphatespecificity pages 1-4, schwer2022cleavagepolyadenylationfactorcft1 pages 15-17, gerasimaite2017inositolpyrophosphatespecificity pages 16-20, gerasimaite2017inositolpyrophosphatespecificity pages 6-9). | High for family-level regulation; moderate for ligand hierarchy in N. crassa | The relevant N. crassa inositol-pyrophosphate species, affinity, regulatory partners, and fold activation are unknown. |
| Biological pathway | Most likely functions in fungal phosphate homeostasis by converting cytosolic ATP phosphate into vacuolar polyphosphate, thereby creating a mobilizable phosphorus store and sequestering polyphosphate away from the cytosol. | Ortholog VTC studies connect synthesis to vacuolar storage and PHO-pathway regulation (tan2025multilayeredregulationof pages 8-10, bentleydesousa2021vtc5islocalized pages 1-2, gerasimaite2017inositolpyrophosphatespecificity pages 6-9). | High for conserved pathway placement; moderate for organism-specific regulation | Direct regulation by the N. crassa phosphate-starvation machinery and the timing of polyphosphate mobilization have not been established for NCU08110. |
| Target-specific phenotype | Unknown. Loss of function is predicted to reduce vacuolar polyphosphate and perturb phosphate buffering, but no NCU08110-specific knockout, localization, biochemical, or physiological phenotype was found. | No direct N. crassa literature; prediction rests on fungal Vtc4 loss-of-function and catalytic-mutant studies (tan2025multilayeredregulationof pages 8-10, schwer2022cleavagepolyadenylationfactorcft1 pages 15-17). | Low for any particular phenotype | Ortholog phenotypes must not be presented as observations in N. crassa; effects on growth, stress resistance, morphology, and virulence remain hypotheses. |
Table: Evidence-calibrated functional annotation of NCU08110/Q7SCX0, separating supplied database assignments from experimentally demonstrated fungal-ortholog biology. It highlights where mechanistic inference is strong and where direct Neurospora crassa evidence is absent.
The target specified by the user is:
This domain/family assignment aligns with characterized fungal Vtc4 architecture. In fission yeast, Vtc4 contains a cytoplasm-facing N-terminal SPX domain, central catalytic polymerase region, and C-terminal membrane anchor; another description identifies an N-terminal triphosphate-tunnel-metalloenzyme-type catalytic module linked to a membrane-associated region (schwer2022cleavagepolyadenylationfactorcft1 pages 15-17, schwer2022cleavagepolyadenylationfactorcft1 pages 12-15). Thus, the supplied NCU08110 annotation is internally and evolutionarily coherent.
No direct NCU08110/Q7SCX0 publication was recovered. In particular, the search found no purified-protein assay, gene-deletion phenotype, fluorescent localization, membrane fractionation, interaction experiment, or target-specific kinetic measurement. All mechanistic statements below are consequently labeled as strong orthology-based inference unless stated otherwise. Literature concerning Saccharomyces cerevisiae or Schizosaccharomyces pombe Vtc4 must not be mistaken for direct evidence in N. crassa.
Experimentally characterized fungal Vtc4 proteins are catalytic polyphosphate polymerases. The enzyme transfers the terminal, γ-phosphate of an NTP to inorganic phosphate, pyrophosphate, or the terminus of an existing polyphosphate chain. For the physiological ATP-dependent reaction, a simplified elongation step is:
ATP + polyPₙ → ADP + polyPₙ₊₁
Initiation can be represented as transfer to a phosphate or pyrophosphate primer. The reaction characterized in yeast is manganese dependent, and conserved arginine residues participate in ATP binding (schwer2022cleavagepolyadenylationfactorcft1 pages 15-17, schwer2022cleavagepolyadenylationfactorcft1 pages 12-15). This supports the supplied EC 2.7.4.1/polyphosphate-kinase annotation for NCU08110.
The safest substrate-specificity conclusion is that ATP is the expected physiological phosphate donor, but strict ATP exclusivity has not been established for NCU08110. The ortholog literature describes transfer from an NTP rather than demonstrating that only ATP is accepted. No Km, Vmax, turnover number, chain-length distribution, primer preference, or Mn²⁺-versus-other-metal comparison is available for Q7SCX0.
Vtc4 is not simply a soluble polyphosphate kinase. In yeast, it functions in a membrane complex that couples polymerization at the cytosolic face to immediate movement of the growing polyphosphate through the membrane and into the vacuolar lumen (schwer2022cleavagepolyadenylationfactorcft1 pages 12-15, bentleydesousa2021vtc5islocalized pages 1-2). This coupling explains the “SPX-dependent polyphosphate polymerase” and “vacuolar membrane polyphosphate polymerase catalytic subunit” descriptions more precisely than the broad alternative name “polyphosphate kinase.”
A recent fungal-phosphate review summarizes cryo-EM evidence for a Vtc4:Vtc3:Vtc1 assembly with 3:1:1 stoichiometry and a membrane region containing 15 transmembrane helices, forming a polyphosphate-selective channel. ATP-dependent synthesis occurs at the channel entrance, followed by transmembrane delivery (tan2025multilayeredregulationof pages 8-10). These structural values derive from yeast-family complexes, not an NCU08110 complex.
The supplied SPX, VTC, VTC-superfamily, DUF202, and VTC-complex-subunit annotations collectively support three functional regions:
In fission yeast, the SPX and catalytic portions face the cytoplasm, which provides access to ATP, Mn²⁺, and soluble inositol-pyrophosphate regulators; the synthesized polymer is delivered in the opposite direction into the vacuolar lumen (schwer2022cleavagepolyadenylationfactorcft1 pages 12-15). This is the most plausible topology for NCU08110, but remains unverified experimentally.
The predicted operational site is the vacuolar membrane. Characterized budding-yeast Vtc4, Vtc1, and Vtc3 associate with that membrane, and the polymerization product accumulates in the vacuolar lumen (gerasimaite2017inositolpyrophosphatespecificity pages 16-20, bentleydesousa2021vtc5islocalized pages 1-2). Accordingly, NCU08110 should be regarded as a vacuolar-membrane enzyme/translocase component, not as a freely soluble cytosolic kinase or plasma-membrane phosphate importer.
The spatial arrangement has an important physiological consequence: potentially disruptive polyphosphate is synthesized at the cytosolic surface but sequestered directly into a lysosome-like compartment. In budding yeast, polyphosphate can exceed 10% of cellular dry weight, illustrating the storage capacity of this system, although this statistic cannot be assigned to N. crassa without measurement (bentleydesousa2021vtc5islocalized pages 1-2).
In budding yeast, the minimal VTC core contains catalytic Vtc4, Vtc1, and either Vtc2 or Vtc3; additional subunits such as Vtc5 regulate complex activity and localization (bentleydesousa2021vtc5islocalized pages 1-2). Vtc4 therefore has two inseparable roles:
The exact NCU08110 partners are unknown. It is reasonable to search the N. crassa proteome for Vtc1-, Vtc2/3-, and Vtc5-like proteins, but neither their interaction with NCU08110 nor the yeast-like stoichiometry should be assumed without co-immunoprecipitation, native complex purification, or structural analysis.
VTC activity is controlled by inositol pyrophosphates acting through SPX domains. In isolated budding-yeast vacuoles, 5-PP-InsP₅ (5-InsP₇) stimulates VTC around 0.5 µM; 1,5-(PP)₂-InsP₄ (InsP₈) is more potent in vitro, whereas 5-InsP₇ is considered the principal activator under standard cellular conditions because it is more abundant (gerasimaite2017inositolpyrophosphatespecificity pages 1-4, gerasimaite2017inositolpyrophosphatespecificity pages 6-9). Related experiments show that VTC can remain assembled but inactive when cells lack the Kcs1-dependent inositol-pyrophosphate signal, and constitutively active SPX alleles can restore polyphosphate accumulation (gerasimaite2017inositolpyrophosphatespecificity pages 16-20, gerasimaite2017inositolpyrophosphatespecificity pages 20-22).
The regulatory response can be large: ortholog studies report approximately 20-fold stimulation by submicromolar inositol pyrophosphates, and InsP₈ can be at least 20-fold more potent than tested InsP₇ isomers under particular in-vitro conditions (schwer2022cleavagepolyadenylationfactorcft1 pages 15-17). Ligand hierarchy is context dependent, however, and these numerical values must not be transferred directly to NCU08110.
Inositol pyrophosphates report cellular phosphate and energetic state. Their binding to SPX modules therefore provides a mechanism by which phosphate sufficiency activates conversion of cytosolic ATP phosphate into vacuolar polyphosphate. Under phosphate limitation, stored polymer can subsequently be mobilized through vacuolar polyphosphatases and phosphate-export systems. A recent synthesis places fungal VTC downstream of PHO/Pho4-controlled phosphate homeostasis and describes inhibition through regulatory SPX–SPX interactions that is relieved by inositol-pyrophosphate binding (tan2025multilayeredregulationof pages 8-10).
For N. crassa, direct regulation of NCU08110 by its phosphate-starvation network has not been demonstrated. The precise activating ligand, regulatory subunit, transcriptional response, and behavior during phosphate upshift or starvation remain open questions.
The strongest predicted process assignments are:
These are precise mechanistic roles rather than broad pleiotropic phenotypes. In fission yeast, Vtc4 deletion or catalytic-site mutation alters inositol-pyrophosphate-linked phosphate-regulon behavior; Vtc2/Vtc4 loss reduced an IP₈-dependent Pho1 response by 37% in one experimental setting (schwer2022cleavagepolyadenylationfactorcft1 pages 15-17). This supports pathway connectivity but is not an expected quantitative effect size for N. crassa.
No 2023–2024 study directly characterizing NCU08110 was identified. The key recent advance relevant to annotation is structural: cryo-EM studies, summarized in a 2025 fungal-phosphate review, recast VTC as an integrated polymerase/channel rather than merely a membrane-associated enzyme. The reported 3:1:1 subunit architecture and 15-helix channel provide a physical explanation for simultaneous synthesis and vacuolar import (tan2025multilayeredregulationof pages 8-10).
The mechanistic foundation remains the 2017 ACS Chemical Biology study showing chemically selective activation of yeast VTC by inositol pyrophosphates, including the distinction between the most potent ligand in vitro and the likely dominant ligand in vivo. Publication: February 2017; URL: https://doi.org/10.1021/acschembio.7b00026 (gerasimaite2017inositolpyrophosphatespecificity pages 1-4, gerasimaite2017inositolpyrophosphatespecificity pages 6-9).
A 2022 mBio study extended the connection between Vtc4 catalytic activity, SPX proteins, inositol-pyrophosphate biology, and phosphate-regulon output in fission yeast. Publication: February 2022; URL: https://doi.org/10.1128/mbio.03476-21 (schwer2022cleavagepolyadenylationfactorcft1 pages 15-17, schwer2022cleavagepolyadenylationfactorcft1 pages 12-15).
A 2021 mBio study provided cell-biological evidence that VTC components operate at the vacuolar membrane and that intracellular trafficking of an accessory regulator controls polyphosphate abundance. Loss of Vtc5 reduced budding-yeast polyphosphate to approximately 20% of wild type. Publication: October 2021; URL: https://doi.org/10.1128/mbio.00994-21 (bentleydesousa2021vtc5islocalized pages 1-2).
NCU08110 itself has no documented industrial, clinical, or agricultural implementation. Its value is presently as a mechanistic and experimental target:
Authoritative studies emphasize that correct membrane localization and complex assembly are integral to VTC function, so overexpressing NCU08110 alone may not increase polyphosphate unless its partner subunits, trafficking, ATP supply, metal cofactor, and inositol-pyrophosphate signaling are also adequate (gerasimaite2017inositolpyrophosphatespecificity pages 16-20, bentleydesousa2021vtc5islocalized pages 1-2).
NCU08110/Q7SCX0 is a predicted vacuolar-membrane VTC4-family catalytic subunit that synthesizes inorganic polyphosphate from cytosolic ATP in a metal-dependent reaction and couples polymer extension to translocation into the vacuolar lumen; its N-terminal SPX domain probably regulates activity in response to inositol-pyrophosphate phosphate-status signals.
The most decisive experiments would be endogenous fluorescent tagging and membrane topology analysis; deletion plus rescue with catalytic- and SPX-site mutants; quantitative polyphosphate measurements under phosphate-replete, starvation, and phosphate-upshift conditions; purification or reconstitution with candidate VTC partners; ATP/NTP and divalent-metal specificity assays; and tests of activation by defined InsP₇/InsP₈ isomers. Until such work is performed, NCU08110 should be described as strongly inferred Vtc4, not as experimentally characterized N. crassa Vtc4.
References
(schwer2022cleavagepolyadenylationfactorcft1 pages 15-17): Beate Schwer, Angad Garg, Ana M. Sanchez, Mindy A. Bernstein, Bradley Benjamin, and Stewart Shuman. Cleavage-polyadenylation factor cft1 and spx domain proteins are agents of inositol pyrophosphate toxicosis in fission yeast. Feb 2022. URL: https://doi.org/10.1128/mbio.03476-21, doi:10.1128/mbio.03476-21. This article has 25 citations and is from a domain leading peer-reviewed journal.
(schwer2022cleavagepolyadenylationfactorcft1 pages 12-15): Beate Schwer, Angad Garg, Ana M. Sanchez, Mindy A. Bernstein, Bradley Benjamin, and Stewart Shuman. Cleavage-polyadenylation factor cft1 and spx domain proteins are agents of inositol pyrophosphate toxicosis in fission yeast. Feb 2022. URL: https://doi.org/10.1128/mbio.03476-21, doi:10.1128/mbio.03476-21. This article has 25 citations and is from a domain leading peer-reviewed journal.
(gerasimaite2017inositolpyrophosphatespecificity pages 16-20): Ruta Gerasimaite, Igor Pavlovic, Samanta Capolicchio, Alexandre Hofer, Andrea Schmidt, Henning J. Jessen, and Andreas Mayer. Inositol pyrophosphate specificity of the spx-dependent polyphosphate polymerase vtc. ACS chemical biology, 12 3:648-653, Feb 2017. URL: https://doi.org/10.1021/acschembio.7b00026, doi:10.1021/acschembio.7b00026. This article has 130 citations and is from a domain leading peer-reviewed journal.
(bentleydesousa2021vtc5islocalized pages 1-2): Amanda Bentley-DeSousa and Michael Downey. Vtc5 is localized to the vacuole membrane by the conserved ap-3 complex to regulate polyphosphate synthesis in budding yeast. mBio, Oct 2021. URL: https://doi.org/10.1128/mbio.00994-21, doi:10.1128/mbio.00994-21. This article has 14 citations and is from a domain leading peer-reviewed journal.
(tan2025multilayeredregulationof pages 8-10): Yanan Tan, Yanda Ning, Siyi Wang, Faqin Li, Xuewei Cao, Qin Wang, and Ang Ren. Multilayered regulation of fungal phosphate metabolism: from molecular mechanisms to ecological roles in the global phosphorus cycle. Life, 15(11):1676, Oct 2025. URL: https://doi.org/10.3390/life15111676, doi:10.3390/life15111676. This article has 10 citations.
(gerasimaite2017inositolpyrophosphatespecificity pages 1-4): Ruta Gerasimaite, Igor Pavlovic, Samanta Capolicchio, Alexandre Hofer, Andrea Schmidt, Henning J. Jessen, and Andreas Mayer. Inositol pyrophosphate specificity of the spx-dependent polyphosphate polymerase vtc. ACS chemical biology, 12 3:648-653, Feb 2017. URL: https://doi.org/10.1021/acschembio.7b00026, doi:10.1021/acschembio.7b00026. This article has 130 citations and is from a domain leading peer-reviewed journal.
(gerasimaite2017inositolpyrophosphatespecificity pages 6-9): Ruta Gerasimaite, Igor Pavlovic, Samanta Capolicchio, Alexandre Hofer, Andrea Schmidt, Henning J. Jessen, and Andreas Mayer. Inositol pyrophosphate specificity of the spx-dependent polyphosphate polymerase vtc. ACS chemical biology, 12 3:648-653, Feb 2017. URL: https://doi.org/10.1021/acschembio.7b00026, doi:10.1021/acschembio.7b00026. This article has 130 citations and is from a domain leading peer-reviewed journal.
(gerasimaite2017inositolpyrophosphatespecificity pages 20-22): Ruta Gerasimaite, Igor Pavlovic, Samanta Capolicchio, Alexandre Hofer, Andrea Schmidt, Henning J. Jessen, and Andreas Mayer. Inositol pyrophosphate specificity of the spx-dependent polyphosphate polymerase vtc. ACS chemical biology, 12 3:648-653, Feb 2017. URL: https://doi.org/10.1021/acschembio.7b00026, doi:10.1021/acschembio.7b00026. This article has 130 citations and is from a domain leading peer-reviewed journal.