Kelch repeat-containing signaling adaptor protein that functions upstream of Ras1 in the Ras1-Scd1-Cdc42 signaling pathway in S. pombe. Essential for mating/conjugation, pheromone response, and maintenance of elongated cell morphology. Ral2 contains three N-terminal Kelch repeats that likely mediate protein-protein interactions with pathway components. Deletion of ral2 phenocopies ras1 deletion, producing spherical cells with no mating activity, while activated Ras1 can rescue ral2 mutants, placing ral2 genetically upstream of ras1. Vegetative growth is unaffected by ral2 loss.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0004601
peroxidase activity
|
IBA
GO_REF:0000033 |
REMOVE |
Summary: This annotation derives from phylogenetic inference based on PANTHER family PTHR43503 (Peroxiredoxin family, Prx6 subfamily). However, ral2 is a 611 AA kelch repeat protein with no peroxiredoxin domains, no conserved catalytic cysteines, and no evidence of peroxidase activity. Its InterPro domain annotations are Kelch-type beta propeller (IPR015915) and SKP1/BTB/POZ superfamily (IPR011333). The PANTHER family assignment appears incorrect, and this annotation should be removed.
|
|
GO:0005829
cytosol
|
IBA
GO_REF:0000033 |
REMOVE |
Summary: This cytosol localization derives from the same incorrect PANTHER peroxiredoxin family assignment. While ral2 may be cytoplasmic, the only experimental localization data (HDA from PMID:16823372) places it at the endoplasmic reticulum. This IBA annotation is unreliable and should be removed.
|
|
GO:0045454
cell redox homeostasis
|
IBA
GO_REF:0000033 |
REMOVE |
Summary: This annotation derives from the incorrect PANTHER peroxiredoxin family assignment. There is no evidence that ral2 plays any role in redox homeostasis. Its characterized function is in Ras signaling, mating, and cell morphology. Should be removed.
|
|
GO:0098869
cellular oxidant detoxification
|
IEA
GO_REF:0000108 |
REMOVE |
Summary: This IEA annotation likely propagates from the same incorrect peroxiredoxin family assignment via logical inference. Ral2 has no known role in oxidant detoxification. All experimental evidence points to a role in Ras signaling and mating.
|
|
GO:0003674
molecular_function
|
ND
GO_REF:0000015 |
ACCEPT |
Summary: The ND (no biological data) annotation for molecular function is appropriate. The specific biochemical activity of ral2 has not been characterized. Based on its kelch repeat domain and genetic interactions, it likely functions as a signaling adaptor or scaffold, but this has not been experimentally demonstrated at the molecular level.
Supporting Evidence:
PMID:2586528
Sequence analysis of the ral2 gene suggests that it encodes a polypeptide of 611 amino acid residues whose predicted amino acid sequence shows no strong homology to any known protein.
file:SCHPO/ral2/ral2-deep-research-falcon.md
Kelch repeats are ~44–56 aa motifs occurring in 5–7 repeats in many proteins and commonly forming **β-propeller structures**, generally functioning as protein–protein interaction modules.
|
|
GO:0031137
regulation of conjugation with cellular fusion
|
IMP
PMID:3071741 Isolation and characterization of Schizosaccharomyces pombe ... |
ACCEPT |
Summary: Well-supported annotation. Ral2 mutants are deficient in conjugation, and the gene was originally isolated by screening for mutants phenotypically similar to ras1-. Multiple copies of ral2 partially rescue ral1- mating defects, confirming its role in regulating conjugation.
Supporting Evidence:
PMID:3071741
We isolated mutants of Schizosaccharomyces pombe which have deformed cell morphology, are deficient in conjugation and poor in sporulation.
PMID:2586528
The disruptants showed the same phenotype as the original ral2 isolates, i.e., they had spherical cells, had no detectable mating activity, and exhibited no response to the mating pheromone, but their vegetative growth was apparently normal.
file:SCHPO/ral2/ral2-deep-research-falcon.md
A major phenotype class associated with ral2 (and related ral loci) is **mating deficiency**, and ral mutants are described as having **roundish (depolarized) morphology**, consistent with impaired Ras1-dependent polarized growth regulation.
|
|
GO:0005783
endoplasmic reticulum
|
HDA
PMID:16823372 ORFeome cloning and global analysis of protein localization ... |
ACCEPT |
Summary: This localization comes from a high-throughput ORFeome YFP-tagging study that determined localization for ~90% of the S. pombe proteome. While high-throughput, this is the only experimental localization data available. ER localization is plausible for a protein involved in Ras signaling, as Ras proteins can signal from endomembranes.
Supporting Evidence:
PMID:16823372
we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein.
file:SCHPO/ral2/ral2-deep-research-falcon.md
No direct subcellular localization evidence for *S. pombe* Ral2 (e.g., microscopy localization) was retrieved in the accessible texts used here; the available sources primarily provide genetic/pathway placement and domain-level inference.
|
|
GO:0032005
signal transduction involved in positive regulation of conjugation with cellular fusion
|
IGI
PMID:2586528 Characterization of the Schizosaccharomyces pombe ral2 gene ... |
ACCEPT |
Summary: Well-supported annotation. The IGI evidence comes from the genetic interaction showing that activated ras1 (ras1Val-17) rescues ral2 mutants, demonstrating that ral2 functions in signal transduction upstream of ras1 to positively regulate conjugation.
Supporting Evidence:
PMID:2586528
Either multiple copies or even a single copy of the ras1Val-17 allele, which is an activated form of ras1, restored rodlike cell morphology and ability to respond to the mating factor to ral2 mutants.
PMID:3071741
These results suggest that the ral1, ral2 and ras1 genes may function in a common pathway in that order.
PMID:2038319
we suggest that this Ras-GTPase cycle involves the ra12 gene product, another positive regulator of Ras1 whose homologs have not been identified in other organisms, which could function either as a second GDP-GTP-exchanging protein or as a factor that negatively regulates Gap1 activity.
file:SCHPO/ral2/ral2-deep-research-falcon.md
Suppressor analyses and epistasis tests indicate that **gap1 null can bypass the requirement for ral2** to maintain Ras in a GTP-bound state, consistent with ral2 acting to promote Ras1 activity in opposition to Gap1.
|
Q: What is the precise molecular function of ral2? Does it act as a scaffold bringing Ras1 together with its GEF, or does it have a different biochemical activity?
Q: Is the ER localization from the high-throughput study accurate, and if so, does ral2 function at the ER membrane to facilitate Ras1 activation at endomembranes?
Q: What is the significance of Ser-604 phosphorylation? Is it regulatory, and which kinase is responsible?
Q: Should the PANTHER family assignment (PTHR43503, Peroxiredoxin Prx6 subfamily) for ral2 be corrected? The protein has kelch repeats, not peroxiredoxin domains.
Q: Does ral2 interact directly with Ras1 protein, or does it act indirectly through other pathway components?
Experiment: Co-immunoprecipitation or yeast two-hybrid assays to test for direct physical interaction between ral2 and ras1, and between ral2 and known pathway components (scd1, gef1, skp1).
Experiment: Structure-function analysis of ral2 kelch repeats by mutagenesis to determine which protein-protein interactions are essential for mating and morphology functions.
Experiment: Live-cell imaging of fluorescently tagged ral2 to confirm ER localization and determine if it colocalizes with Ras1 at specific membrane compartments.
Experiment: Phospho-mutant analysis (S604A, S604D) to determine if Ser-604 phosphorylation regulates ral2 function in mating or morphology.
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 requested target is ral2 from Schizosaccharomyces pombe (fission yeast), corresponding to a Ras-pathway regulatory factor historically described as a “putative activator of Ras1” and as a “Ras1–Scd pathway protein,” rather than the Ral small-GTPase family known in metazoans. (imai1991identificationofa pages 3-5, imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6, hakuno1996theschizosaccharomycespombe pages 2-4, kawamukai2024regulationofsexual pages 3-3)
A key point for identity verification is that the gene symbol “ral2” is used in older fission-yeast Ras1 signaling genetics, where “ral” denotes Ras-activation/related loci (ral1/scd1, ral2, ral3/scd2) rather than Ras-like small GTPases. (hakuno1996theschizosaccharomycespombe pages 2-4)
In S. pombe, Ras1 functions as a signaling hub important for mating/sexual differentiation and polarized growth. Genetic analyses place ral2 among factors that positively regulate Ras1 signaling and thereby influence mating efficiency and cell morphology. (hakuno1996theschizosaccharomycespombe pages 2-4, imai1991identificationofa pages 3-5, imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6)
In the Ras GTPase cycle, Ras activity is set by opposing activities: guanine nucleotide exchange (activators) versus GTP hydrolysis promotion (GAPs). In the available primary genetic evidence, ral2 is treated as a positive regulator of Ras1 whose mechanism was unresolved: the ral2 product was hypothesized either to function as a GDP→GTP exchange-type activator for Ras1 or to act indirectly by negatively regulating the Ras1 GAP Gap1, thereby increasing Ras1-GTP. (imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6)
Kelch repeats are ~44–56 aa motifs occurring in 5–7 repeats in many proteins and commonly forming β-propeller structures, generally functioning as protein–protein interaction modules. A broad phylogenetic analysis of the Kelch-repeat superfamily explicitly lists a fission yeast protein “Ral-2” as a Kelch-repeat protein with “Kelch and unique” architecture. (prag2003molecularphylogenyof pages 11-13)
Across independent fission-yeast genetics studies, ral2 is most consistently supported as a positive regulator of Ras1 signaling (a “putative activator of Ras1”), functioning in Ras1-dependent control of mating competence and cell shape/polarized growth. (hakuno1996theschizosaccharomycespombe pages 2-4, imai1991identificationofa pages 3-5, imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6)
A major phenotype class associated with ral2 (and related ral loci) is mating deficiency, and ral mutants are described as having roundish (depolarized) morphology, consistent with impaired Ras1-dependent polarized growth regulation. (hakuno1996theschizosaccharomycespombe pages 2-4, imai1991identificationofa pages 1-2)
A strong line of evidence comes from suppressor/epistasis mapping around Ras1 regulation:
- Suppressor analyses and epistasis tests indicate that gap1 null can bypass the requirement for ral2 to maintain Ras in a GTP-bound state, consistent with ral2 acting to promote Ras1 activity in opposition to Gap1. (imai1991identificationofa pages 3-5)
- Point mutations in the ras1 ORF can suppress ral2 defects, supporting the idea that ral2 acts upstream of or on Ras1 activation rather than simply affecting ras1 expression. (imai1991identificationofa pages 5-6)
Collectively, these results support that Ral2’s primary role is control of Ras1 activation state, impacting mating signaling output and morphogenesis. (imai1991identificationofa pages 3-5, imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6)
Multiple sources (including a comparative fungal study summarizing S. pombe work) describe S. pombe Ral2 as containing three Kelch repeats at its N-terminus, and place it in the Ras1–Scd pathway. (qu2021poral2isinvolved pages 3-5)
Additionally, a Kelch-repeat phylogeny includes S. pombe “Ral-2” as a Kelch-repeat protein with a “Kelch and unique” architecture (and does not present it as a canonical BTB/Kelch protein). (prag2003molecularphylogenyof pages 11-13)
A Pyricularia/Magnaporthe homolog (PoRal2) is described as containing N-terminal Kelch repeats and a C-terminal BTB domain, but this does not, by itself, constitute direct experimental or sequence-annotation proof that S. pombe Ral2 contains a BTB domain. (qu2021poral2isinvolved pages 3-5)
The older Kelch-repeat phylogeny explicitly notes that yeast Kelch proteins studied at the time did not correspond to BTB/Kelch proteins, even while listing fission yeast Ral-2 among Kelch proteins. (prag2003molecularphylogenyof pages 11-13)
Therefore, within the tool-retrieved literature here, Kelch-repeat status is supported, but BTB/POZ-domain assignment for S. pombe Ral2 is not conclusively supported (and should be verified directly from UniProt/PomBase sequence/domain annotations or the original primary papers). (qu2021poral2isinvolved pages 3-5, prag2003molecularphylogenyof pages 11-13)
No direct subcellular localization evidence for S. pombe Ral2 (e.g., microscopy localization) was retrieved in the accessible texts used here; the available sources primarily provide genetic/pathway placement and domain-level inference. (imai1991identificationofa pages 3-5, imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6, hakuno1996theschizosaccharomycespombe pages 2-4)
Direct 2023–2024 primary research specifically on S. pombe ral2 was not retrieved in the current tool run; however, two relevant “recent” contributions provide updated context:
1) 2024 review of sexual differentiation initiation in S. pombe: ral2 is included as a “Ras1–Scd pathway protein” in a curated pathway table, reflecting continued recognition of ral2 as a Ras-pathway component in modern syntheses of mating control. Publication date: March 2024. URL: https://doi.org/10.1093/bbb/zbae019 (kawamukai2024regulationofsexual pages 3-3)
2) General 2023–2024 advances in BTB/Kelch and ubiquitin-ligase adaptor biology are extensive, but because a BTB domain for S. pombe Ral2 is not directly supported in the retrieved evidence, those advances can only be applied cautiously as hypothesis-generating context rather than as ral2-specific updates. (prag2003molecularphylogenyof pages 11-13, qu2021poral2isinvolved pages 3-5)
The clearest real-world “implementation” of ral2 biology is as part of the S. pombe toolkit for dissecting conserved Ras signaling logic (Ras activation/deactivation control; mating signaling output; polarized growth). Primary genetics demonstrates how upstream regulators (ral2; gap1) and Ras1 alleles interact to tune Ras activation state and downstream phenotypes. (imai1991identificationofa pages 3-5, imai1991identificationofa pages 5-6)
Ral2 homologs in plant-pathogenic fungi have been studied in infection-related development (e.g., appressorium formation). A 2021 study explicitly frames a rice blast fungus homolog as “homologous to S. pombe Ral2,” leveraging the fission yeast pathway context to motivate functional studies in pathogenesis. Publication date: September 2021. URL: https://doi.org/10.3389/fpls.2021.702368 (qu2021poral2isinvolved pages 3-5)
This is not a direct application of S. pombe ral2 in industry, but it is a practical example of how functional inference from yeast signaling modules informs pathogenic-fungus gene characterization. (qu2021poral2isinvolved pages 3-5)
The following table distinguishes direct evidence (genetic/pathway) from secondary/inferred claims (e.g., specific protein–protein interactions; BTB domain assignment in S. pombe):
| Claim category | Specific claim | Evidence source (paper) | Pub year | DOI/URL | Evidence snippet (paraphrased) | Confidence |
|---|---|---|---|---|---|---|
| identity | The target in the literature is Schizosaccharomyces pombe ral2, a Ras1-pathway regulatory gene/product, not a Ras-family small GTPase. | Imai et al., Mol Cell Biol; Hakuno et al., Genes Cells; Kawamukai, Biosci Biotechnol Biochem | 1991; 1996; 2024 | https://doi.org/10.1128/mcb.11.6.3088-3094.1991 ; https://doi.org/10.1046/j.1365-2443.1996.27029.x ; https://doi.org/10.1093/bbb/zbae019 | Multiple sources describe ral2 as a “putative activator of Ras1” or “Ras1-Scd pathway protein,” distinguishing it from ras1 itself. (imai1991identificationofa pages 3-5, imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6, hakuno1996theschizosaccharomycespombe pages 2-4, kawamukai2024regulationofsexual pages 3-3) | High |
| domains | S. pombe Ral2 is reported to contain N-terminal kelch repeats. | Qu et al., Front Plant Sci | 2021 | https://doi.org/10.3389/fpls.2021.702368 | Comparative discussion of S. pombe Ral2 states it has three kelch repeats at the N-terminus and belongs to the Ras1-Scd pathway context. (qu2021poral2isinvolved pages 1-2, qu2021poral2isinvolved pages 3-5) | Medium |
| domains | Older kelch-family phylogeny lists S. pombe Ral-2 as a kelch-repeat protein with “Kelch and unique” architecture, not as a canonical BTB/kelch protein. | Prag & Adams, BMC Bioinformatics | 2003 | https://doi.org/10.1186/1471-2105-4-42 | Table-based annotation places S. pombe Ral-2 among kelch-repeat proteins and notes yeasts lacked BTB/kelch proteins in that analysis. (prag2003molecularphylogenyof pages 11-13) | Medium |
| domains | Direct support for a BTB/POZ domain in S. pombe Ral2 is not established by the gathered primary evidence; BTB is explicit for the Pyricularia homolog, not unequivocally for S. pombe in these texts. | Qu et al., Front Plant Sci; Prag & Adams, BMC Bioinformatics | 2021; 2003 | https://doi.org/10.3389/fpls.2021.702368 ; https://doi.org/10.1186/1471-2105-4-42 | The fungal homolog PoRal2 is described with a C-terminal BTB domain, but the gathered S. pombe-focused evidence only clearly supports kelch repeats and Ras1-pathway assignment. (qu2021poral2isinvolved pages 11-13, qu2021poral2isinvolved pages 3-5, prag2003molecularphylogenyof pages 11-13) | Medium |
| function | ral2 likely functions as a positive regulator/activator of Ras1. | Imai et al., Mol Cell Biol; Hakuno et al., Genes Cells | 1991; 1996 | https://doi.org/10.1128/mcb.11.6.3088-3094.1991 ; https://doi.org/10.1046/j.1365-2443.1996.27029.x | Genetic studies repeatedly frame ral2 as a putative Ras1 activator; the mechanism remained unresolved. (hakuno1996theschizosaccharomycespombe pages 2-4, imai1991identificationofa pages 3-5, imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6) | High |
| pathway | ral2 acts in the Ras1-Scd signaling pathway tied to mating and morphogenesis. | Qu et al., Front Plant Sci; Kawamukai, Biosci Biotechnol Biochem | 2021; 2024 | https://doi.org/10.3389/fpls.2021.702368 ; https://doi.org/10.1093/bbb/zbae019 | Recent review and comparative paper both label ral2 as a Ras1-Scd pathway protein. (qu2021poral2isinvolved pages 11-13, qu2021poral2isinvolved pages 3-5, kawamukai2024regulationofsexual pages 3-3) | High |
| pathway | Genetic evidence places ral2 upstream of or affecting Ras1 activation, with intimate linkage to the Ras-GTPase cycle and interaction logic involving Gap1. | Imai et al., Mol Cell Biol | 1991 | https://doi.org/10.1128/mcb.11.6.3088-3094.1991 | Suppressor and epistasis analyses showed gap1 null could bypass ral2 requirement for maintaining Ras1-GTP, supporting a role in Ras1 activation control. (imai1991identificationofa pages 3-5, imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6) | High |
| phenotype | ral2 mutants are associated with mating deficiency. | Hakuno et al., Genes Cells; Imai et al., Mol Cell Biol | 1996; 1991 | https://doi.org/10.1046/j.1365-2443.1996.27029.x ; https://doi.org/10.1128/mcb.11.6.3088-3094.1991 | ral genes, including ral2, were cloned from mutants defective in mating; loss of ral2 gives phenotypes similar to reduced Ras1 signaling. (hakuno1996theschizosaccharomycespombe pages 2-4, imai1991identificationofa pages 1-2) | High |
| phenotype | ral2 mutants show roundish/abnormal cell morphology, linking ral2 to polarized growth control. | Hakuno et al., Genes Cells | 1996 | https://doi.org/10.1046/j.1365-2443.1996.27029.x | The ral mutant class is described as mating-deficient with roundish morphology, and ral-linked signaling is tied to Ras1-dependent morphology regulation. (hakuno1996theschizosaccharomycespombe pages 2-4) | High |
| phenotype | Earlier comparative discussion also links S. pombe ral2 to control of cell morphology, conjugation/mating, and sporulation. | Qu et al., Front Plant Sci | 2021 | https://doi.org/10.3389/fpls.2021.702368 | Review-style summary of prior S. pombe literature states Ral2 participates in morphology, conjugation, and sporulation; this is secondary reporting of older work. (qu2021poral2isinvolved pages 1-2) | Medium |
| interactions | Evidence from gathered texts supports a functional/genetic relationship between Ral2 and Ras1, and between Ral2 and Gap1. | Imai et al., Mol Cell Biol | 1991 | https://doi.org/10.1128/mcb.11.6.3088-3094.1991 | ras1 activating mutations suppress ral2 defects, and gap1 epistasis indicates ral2 operates in the Ras1 regulatory cycle. (imai1991identificationofa pages 3-5, imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6) | High |
| interactions | Secondary reporting indicates S. pombe Ral2 has been reported to interact with Gef1 and Skp1, but these claims were not directly verified here from the original S. pombe primary papers. | Qu et al., Front Plant Sci | 2021 | https://doi.org/10.3389/fpls.2021.702368 | Comparative fungal paper summarizes earlier S. pombe work saying Ral2 interacts with Gef1 and Skp1; this remains indirect evidence in the present retrieval set. (qu2021poral2isinvolved pages 1-2, qu2021poral2isinvolved pages 11-13) | Low |
| notes | Mechanistically, ral2 was hypothesized to act either as a GDP-GTP exchange-type activator for Ras1 or as an indirect negative regulator of Gap1, but the exact biochemical mechanism remained unresolved. | Imai et al., Mol Cell Biol | 1991 | https://doi.org/10.1128/mcb.11.6.3088-3094.1991 | Authors explicitly discuss alternative mechanistic models for how ral2 promotes Ras1 activity. (imai1991identificationofa pages 1-2, imai1991identificationofa pages 5-6) | High |
| notes | Direct primary paper not retrieved here: Fukui et al. 1989 is repeatedly cited as the original ral2 characterization, but only secondary references to it were available in the current evidence set. | Fukui et al., Mol Cell Biol (cited as unobtainable in search results) | 1989 | https://doi.org/10.1128/mcb.9.12.5617-5622.1989 | The foundational paper on ral2 characterization was identified but not retrievable in the current tool output; conclusions attributed to it here are therefore partly mediated through later sources. (qu2021poral2isinvolved pages 1-2, hakuno1996theschizosaccharomycespombe pages 2-4) | High |
Table: This table consolidates the gathered evidence for S. pombe ral2/SPBC21.05c (UniProt P15258), separating direct support from indirect or secondary claims. It is useful for distinguishing well-supported conclusions about Ras1-pathway function and phenotype from less certain domain and interaction annotations.
The foundational primary paper “Characterization of the S. pombe ral2 gene implicated in activation of the ras1 gene product” (Fukui et al., 1989; Molecular and Cellular Biology) was identified but not retrievable within this tool session. Consequently, some frequently repeated statements (e.g., specific domain architecture details beyond Kelch repeats; direct physical interactions such as with Skp1 and Gef1) are currently supported only via secondary reporting in later literature rather than by direct quotation from the 1989 primary source. (qu2021poral2isinvolved pages 1-2, hakuno1996theschizosaccharomycespombe pages 2-4)
References
(imai1991identificationofa pages 3-5): Yoshiyuki Imai, Sanae Miyake, David A. Hughes, and Masayuki Yamamoto. Identification of a gtpase-activating protein homolog in schizosaccharomyces pombe. Molecular and Cellular Biology, 11:3088-3094, Jun 1991. URL: https://doi.org/10.1128/mcb.11.6.3088-3094.1991, doi:10.1128/mcb.11.6.3088-3094.1991. This article has 93 citations and is from a domain leading peer-reviewed journal.
(imai1991identificationofa pages 1-2): Yoshiyuki Imai, Sanae Miyake, David A. Hughes, and Masayuki Yamamoto. Identification of a gtpase-activating protein homolog in schizosaccharomyces pombe. Molecular and Cellular Biology, 11:3088-3094, Jun 1991. URL: https://doi.org/10.1128/mcb.11.6.3088-3094.1991, doi:10.1128/mcb.11.6.3088-3094.1991. This article has 93 citations and is from a domain leading peer-reviewed journal.
(imai1991identificationofa pages 5-6): Yoshiyuki Imai, Sanae Miyake, David A. Hughes, and Masayuki Yamamoto. Identification of a gtpase-activating protein homolog in schizosaccharomyces pombe. Molecular and Cellular Biology, 11:3088-3094, Jun 1991. URL: https://doi.org/10.1128/mcb.11.6.3088-3094.1991, doi:10.1128/mcb.11.6.3088-3094.1991. This article has 93 citations and is from a domain leading peer-reviewed journal.
(hakuno1996theschizosaccharomycespombe pages 2-4): Fumihiko Hakuno, David A. Hughes, and Masayuki Yamamoto. The schizosaccharomyces pombe mra1 gene, which is required for cell growth and mating, can suppress the mating inefficiency caused by a deficit in the ras1 activity. Genes to Cells, 1:303-315, Mar 1996. URL: https://doi.org/10.1046/j.1365-2443.1996.27029.x, doi:10.1046/j.1365-2443.1996.27029.x. This article has 13 citations and is from a peer-reviewed journal.
(kawamukai2024regulationofsexual pages 3-3): Makoto Kawamukai. Regulation of sexual differentiation initiation in schizosaccharomyces pombe. Bioscience, biotechnology, and biochemistry, 88:475-492, Mar 2024. URL: https://doi.org/10.1093/bbb/zbae019, doi:10.1093/bbb/zbae019. This article has 16 citations.
(prag2003molecularphylogenyof pages 11-13): Soren Prag and Josephine C Adams. Molecular phylogeny of the kelch-repeat superfamily reveals an expansion of btb/kelch proteins in animals. BMC Bioinformatics, 4:42-42, Sep 2003. URL: https://doi.org/10.1186/1471-2105-4-42, doi:10.1186/1471-2105-4-42. This article has 213 citations and is from a peer-reviewed journal.
(qu2021poral2isinvolved pages 3-5): Yingmin Qu, Jing Wang, Pengyun Huang, Xiaohong Liu, Jianping Lu, and Fu-Cheng Lin. Poral2 is involved in appressorium formation and virulence via pmk1 mapk pathways in the rice blast fungus pyricularia oryzae. Frontiers in Plant Science, Sep 2021. URL: https://doi.org/10.3389/fpls.2021.702368, doi:10.3389/fpls.2021.702368. This article has 28 citations.
(qu2021poral2isinvolved pages 1-2): Yingmin Qu, Jing Wang, Pengyun Huang, Xiaohong Liu, Jianping Lu, and Fu-Cheng Lin. Poral2 is involved in appressorium formation and virulence via pmk1 mapk pathways in the rice blast fungus pyricularia oryzae. Frontiers in Plant Science, Sep 2021. URL: https://doi.org/10.3389/fpls.2021.702368, doi:10.3389/fpls.2021.702368. This article has 28 citations.
(qu2021poral2isinvolved pages 11-13): Yingmin Qu, Jing Wang, Pengyun Huang, Xiaohong Liu, Jianping Lu, and Fu-Cheng Lin. Poral2 is involved in appressorium formation and virulence via pmk1 mapk pathways in the rice blast fungus pyricularia oryzae. Frontiers in Plant Science, Sep 2021. URL: https://doi.org/10.3389/fpls.2021.702368, doi:10.3389/fpls.2021.702368. This article has 28 citations.
Ral2 is a Ras1-Scd pathway protein essential for mating/conjugation and cell morphology in S. pombe. It functions upstream of Ras1 in a signaling pathway that controls both mating pheromone response and elongated cell shape via the Ras1-Scd1-Cdc42 axis.
The Ras1 signaling pathway in S. pombe:
- Morphology branch: Ras1 -> Scd1 (GEF for Cdc42) -> Cdc42 -> Shk1 (PAK kinase) -> cell polarity
- Mating branch: Ras1 -> Byr2 -> MAPK cascade -> mating gene expression
- Ral2 acts upstream of Ras1, likely facilitating Ras1 activation
- The Kelch repeats in ral2 mediate protein-protein interactions with pathway components
Ral2 is assigned to PANTHER family PTHR43503 (Peroxiredoxin family, Prx6 subfamily). This appears to be an INCORRECT family assignment:
The specific molecular function of ral2 is not well characterized at the biochemical level. It is NOT a GEF, GAP, or kinase. Based on its kelch repeat domain and genetic interactions, it likely functions as a signaling adaptor/scaffold that facilitates Ras1 activation, possibly by:
- Bringing together pathway components via kelch-mediated protein-protein interactions
- Facilitating the action of a Ras GEF on Ras1
- The ND (no biological data) annotation for MF is appropriate given the lack of biochemical characterization
ral2 deletion does NOT affect vegetative growth - only mating and cell morphology are impaired PMID:2586528.
Exported on March 22, 2026 at 12:46 AM
Organism: Schizosaccharomyces pombe
Sequence:
MSEVKRNISLRNSTNIFTSTFSLSSNNVPKPLIGESVIKYGDEAFVYGGRDALNAQLVNDMYVVDLNTCSWKQVEYQGNQKPIPRYFHSGDLWNNKLIFFGGMGFNDDTKCLYVLNDIDIYDIETKQWSHIPGMITENQTNDDAKEVNGSDVDEKSKHLYPSARYGHLHCVLDHYLIIFCGQDLSNSYIEEINIFDLDSGKWVFKSLFNHHCGIYRSNCVVINKDSEFLQMCRPINTTQDSNEHSIGSLFFYLNYNFVNVKRQVIYLELFELDTAESEKKSAALAKDNNQSFRFLELDVTEKFLSSAMPPGLRFPAVNILGDNLILSGIYLTSSRQAFVLWVYSLDKELWLQLDMLGVLNHGSWFKCLVLDCTNRFVVFGNKTRKLTQDYNLRQSNYDHIVFIELEGYGVYRKPQMGRVTERSEQLGKLLLNGISDMEILTIERMHIPCLSRMLYKRWPAFQKIMDRAVEKNQEAFQAEVSQLGPQLTDLPFSSIHSTGSRALYMPYSFETCSAFLHYIYCGTLNGSYCTAKNLCNLLILCKGFEGLETFFAYIVHLLHGVLNRNNVKLIYETAALTGAKGLQLRALRRIARIEQGGTAISPTSPLPNLDD
I begin by examining the domain architecture. The N-terminal half harbors IPR015915 (Kelch-type beta-propeller homologous_superfamily, residues 6–382), a canonical six-bladed beta-propeller that creates a solvent-exposed, concave binding surface for sequence-specific substrate recognition. This arrangement is followed by IPR011333 (SKP1/BTB/POZ domain superfamily, residues 419–591), a C-terminal BTB/Skp1-like fold that mediates high-affinity assembly with cullin-based ubiquitin ligase cores and other adaptor modules. The linear order—an N-terminal Kelch beta-propeller followed by a C-terminal BTB/Skp1-like region—forms a classic BTB–Kelch adaptor architecture: the beta-propeller dictates substrate capture, while the BTB/Skp1-like module nucleates or bridges the cullin–RING ubiquitin ligase scaffold.
This architecture causally specifies molecular function as protein binding (GO:0003674). The Kelch beta-propeller enforces selective binding to client proteins via loop-mediated recognition, and the BTB/Skp1-like region provides avid protein–protein interfaces for ligase core components. Together, these features enforce a multivalent adaptor role that concentrates target proteins into ubiquitination-competent assemblies.
From this binding-centric mechanism, the biological process follows: an adaptor that recruits substrates to cullin–RING ligase machinery promotes their ubiquitin tagging and turnover. Thus, the architecture drives protein ubiquitination and downstream proteostasis pathways, aligning with protein ubiquitination as a core process. In fission yeast, such turnover is essential for cell cycle transitions and developmental switches; a Kelch–BTB adaptor would efficiently route specific regulators into the ubiquitylation pathway.
Cellular localization is inferred from the soluble, adaptor-driven nature of the assembly. The absence of transmembrane segments and the soluble beta-propeller/BTB composition argue for a cytoplasmic operating environment, consistent with cytoplasm (GO:0005737). This cytoplasmic setting allows broad access to soluble substrates and to cytosolic pools of cullin–RING ligase components that transiently assemble during substrate modification.
Mechanistically, I hypothesize that the protein acts as a cytoplasmic substrate adaptor that couples Kelch-mediated substrate capture to BTB/Skp1-like engagement of a cullin–RING core. The BTB/Skp1-like region likely recruits or bridges to a CRL module (for example, Cul3- or CRL4-class assemblies), positioning captured substrates for ubiquitin transfer from E2 conjugating enzymes. Likely interaction partners include cullin family scaffolds and RING-finger catalytic subunits, as well as Skp1-like adaptors; transient contacts with E2 enzymes would accompany substrate handoff into the ubiquitination cascade. In fission yeast, this would collectively tune cytoplasmic protein stability to support rapid remodeling of cytosolic regulatory networks.
A cytoplasmic adaptor that uses an N-terminal beta-propeller to recognize client proteins and a C-terminal BTB/Skp1-like module to assemble with ubiquitin ligase cores. By bridging substrates to cullin–RING machinery, it promotes their ubiquitin tagging and turnover in the cytoplasm, thereby shaping proteostasis and regulatory pathways that require swift, selective protein degradation.
Probable adapter protein.
IPR015915, homologous_superfamily) — residues 6-382IPR011333, homologous_superfamily) — residues 419-591Molecular Function: molecular_function (GO:0003674), molecular adaptor activity (GO:0060090), protein-macromolecule adaptor activity (GO:0030674)
Biological Process: biological_process (GO:0008150), response to stimulus (GO:0050896), regulation of biological process (GO:0050789), cellular process (GO:0009987), signaling (GO:0023052), biological regulation (GO:0065007), positive regulation of biological process (GO:0048518), positive regulation of conjugation with cellular fusion (GO:0031139), cellular response to stimulus (GO:0051716), regulation of conjugation with cellular fusion (GO:0031137), cell communication (GO:0007154), signal transduction (GO:0007165), regulation of cellular process (GO:0050794), signal transduction involved in positive regulation of conjugation with cellular fusion (GO:0032005)
Cellular Component: cellular_component (GO:0005575), cellular anatomical entity (GO:0110165), intracellular anatomical structure (GO:0005622), organelle (GO:0043226), cytoplasm (GO:0005737), endomembrane system (GO:0012505), intracellular organelle (GO:0043229), endoplasmic reticulum (GO:0005783), membrane-bounded organelle (GO:0043227), intracellular membrane-bounded organelle (GO:0043231)
Generated by BioReason
Source: ral2-bioreason-rl-predictions.md
BioReason's functional summary states:
A cytoplasmic adaptor that uses an N-terminal beta-propeller to recognize client proteins and a C-terminal BTB/Skp1-like module to assemble with ubiquitin ligase cores. By bridging substrates to cullin-RING machinery, it promotes their ubiquitin tagging and turnover in the cytoplasm, thereby shaping proteostasis and regulatory pathways that require swift, selective protein degradation.
The domain architecture description (N-terminal Kelch beta-propeller + C-terminal BTB/Skp1-like fold) is correct and aligns with the InterPro annotations (IPR015915, IPR011333). The "adaptor" characterization is partially right -- the curated review describes ral2 as a signaling adaptor. However, the specific claim about ubiquitin ligase function is unsupported and likely incorrect.
The curated review establishes that ral2 functions upstream of Ras1 in the Ras1-Scd1-Cdc42 signaling pathway, essential for mating/conjugation and cell morphology maintenance. Key findings (PMID:2586528, PMID:3071741):
- ral2 deletion phenocopies ras1 deletion (spherical cells, no mating)
- Activated Ras1 rescues ral2 mutants, placing ral2 genetically upstream of ras1
- The ND (no biological data) annotation for molecular function reflects that the specific biochemical activity is uncharacterized
BioReason misses the entire mating/conjugation biology, which is the experimentally characterized function (IMP and IGI evidence). The ubiquitin ligase hypothesis, while structurally plausible for a Kelch-BTB protein, has no experimental support for ral2.
The localization claim of cytoplasm is also inconsistent with the curated review, which accepts endoplasmic reticulum (GO:0005783) as the experimentally determined localization (HDA, PMID:16823372).
Comparison with interpro2go:
There are no interpro2go (GO_REF:0000002) annotations in the curated review for ral2. The existing IBA annotations come from PANTHER (GO_REF:0000033) and are noted as being from an incorrect family assignment (PTHR43503, Peroxiredoxin family), leading to erroneous peroxidase activity, cell redox homeostasis, and cytosol annotations -- all marked REMOVE. BioReason avoids the peroxiredoxin error (which is good) but instead fabricates an equally unsupported ubiquitin ligase narrative. BioReason correctly identifies the Kelch-BTB architecture, which interpro2go missed entirely due to the wrong PANTHER family, but then goes wrong on the functional inference.
The trace correctly identifies the Kelch-BTB architecture and reasonably infers an adaptor function. However, it then defaults to the most common Kelch-BTB paradigm (CRL ubiquitin ligase substrate adaptor) without considering the organism-specific experimental evidence. The phrase "promotes their ubiquitin tagging and turnover" is speculative extrapolation from domain architecture alone.
---
id: P15258
gene_symbol: ral2
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:284812
label: Schizosaccharomyces pombe (strain 972 / ATCC 24843)
description: >-
Kelch repeat-containing signaling adaptor protein that functions upstream of
Ras1 in the Ras1-Scd1-Cdc42 signaling pathway in S. pombe. Essential for
mating/conjugation, pheromone response, and maintenance of elongated cell
morphology. Ral2 contains three N-terminal Kelch repeats that likely mediate
protein-protein interactions with pathway components. Deletion of ral2
phenocopies ras1 deletion, producing spherical cells with no mating activity,
while activated Ras1 can rescue ral2 mutants, placing ral2 genetically
upstream of ras1. Vegetative growth is unaffected by ral2 loss.
existing_annotations:
- term:
id: GO:0004601
label: peroxidase activity
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
This annotation derives from phylogenetic inference based on PANTHER
family PTHR43503 (Peroxiredoxin family, Prx6 subfamily). However, ral2
is a 611 AA kelch repeat protein with no peroxiredoxin domains, no
conserved catalytic cysteines, and no evidence of peroxidase activity.
Its InterPro domain annotations are Kelch-type beta propeller
(IPR015915) and SKP1/BTB/POZ superfamily (IPR011333). The PANTHER
family assignment appears incorrect, and this annotation should be
removed.
action: REMOVE
- term:
id: GO:0005829
label: cytosol
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
This cytosol localization derives from the same incorrect PANTHER
peroxiredoxin family assignment. While ral2 may be cytoplasmic, the
only experimental localization data (HDA from PMID:16823372) places it
at the endoplasmic reticulum. This IBA annotation is unreliable and
should be removed.
action: REMOVE
- term:
id: GO:0045454
label: cell redox homeostasis
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
This annotation derives from the incorrect PANTHER peroxiredoxin family
assignment. There is no evidence that ral2 plays any role in redox
homeostasis. Its characterized function is in Ras signaling, mating,
and cell morphology. Should be removed.
action: REMOVE
- term:
id: GO:0098869
label: cellular oxidant detoxification
evidence_type: IEA
original_reference_id: GO_REF:0000108
review:
summary: >-
This IEA annotation likely propagates from the same incorrect
peroxiredoxin family assignment via logical inference. Ral2 has no
known role in oxidant detoxification. All experimental evidence points
to a role in Ras signaling and mating.
action: REMOVE
- term:
id: GO:0003674
label: molecular_function
evidence_type: ND
original_reference_id: GO_REF:0000015
review:
summary: >-
The ND (no biological data) annotation for molecular function is
appropriate. The specific biochemical activity of ral2 has not been
characterized. Based on its kelch repeat domain and genetic
interactions, it likely functions as a signaling adaptor or scaffold,
but this has not been experimentally demonstrated at the molecular
level.
action: ACCEPT
supported_by:
- reference_id: PMID:2586528
supporting_text: >-
Sequence analysis of the ral2 gene suggests that it encodes a
polypeptide of 611 amino acid residues whose predicted amino acid
sequence shows no strong homology to any known protein.
- reference_id: file:SCHPO/ral2/ral2-deep-research-falcon.md
supporting_text: |-
Kelch repeats are ~44–56 aa motifs occurring in 5–7 repeats in many proteins and commonly forming **β-propeller structures**, generally functioning as protein–protein interaction modules.
- term:
id: GO:0031137
label: regulation of conjugation with cellular fusion
evidence_type: IMP
original_reference_id: PMID:3071741
review:
summary: >-
Well-supported annotation. Ral2 mutants are deficient in conjugation,
and the gene was originally isolated by screening for mutants
phenotypically similar to ras1-. Multiple copies of ral2 partially
rescue ral1- mating defects, confirming its role in regulating
conjugation.
action: ACCEPT
supported_by:
- reference_id: PMID:3071741
supporting_text: >-
We isolated mutants of Schizosaccharomyces pombe which have
deformed cell morphology, are deficient in conjugation and poor in
sporulation.
- reference_id: PMID:2586528
supporting_text: >-
The disruptants showed the same phenotype as the original ral2
isolates, i.e., they had spherical cells, had no detectable mating
activity, and exhibited no response to the mating pheromone, but
their vegetative growth was apparently normal.
- reference_id: file:SCHPO/ral2/ral2-deep-research-falcon.md
supporting_text: |-
A major phenotype class associated with ral2 (and related ral loci) is **mating deficiency**, and ral mutants are described as having **roundish (depolarized) morphology**, consistent with impaired Ras1-dependent polarized growth regulation.
- term:
id: GO:0005783
label: endoplasmic reticulum
evidence_type: HDA
original_reference_id: PMID:16823372
review:
summary: >-
This localization comes from a high-throughput ORFeome YFP-tagging
study that determined localization for ~90% of the S. pombe proteome.
While high-throughput, this is the only experimental localization data
available. ER localization is plausible for a protein involved in Ras
signaling, as Ras proteins can signal from endomembranes.
action: ACCEPT
supported_by:
- reference_id: PMID:16823372
supporting_text: >-
we determined the localization of 4,431 proteins, corresponding to
approximately 90% of the fission yeast proteome, by tagging each
ORF with the yellow fluorescent protein.
- reference_id: file:SCHPO/ral2/ral2-deep-research-falcon.md
supporting_text: |-
No direct subcellular localization evidence for *S. pombe* Ral2 (e.g., microscopy localization) was retrieved in the accessible texts used here; the available sources primarily provide genetic/pathway placement and domain-level inference.
- term:
id: GO:0032005
label: signal transduction involved in positive regulation of conjugation with
cellular fusion
evidence_type: IGI
original_reference_id: PMID:2586528
review:
summary: >-
Well-supported annotation. The IGI evidence comes from the genetic
interaction showing that activated ras1 (ras1Val-17) rescues ral2
mutants, demonstrating that ral2 functions in signal transduction
upstream of ras1 to positively regulate conjugation.
action: ACCEPT
supported_by:
- reference_id: PMID:2586528
supporting_text: >-
Either multiple copies or even a single copy of the ras1Val-17
allele, which is an activated form of ras1, restored rodlike cell
morphology and ability to respond to the mating factor to ral2
mutants.
- reference_id: PMID:3071741
supporting_text: >-
These results suggest that the ral1, ral2 and ras1 genes may
function in a common pathway in that order.
- reference_id: PMID:2038319
supporting_text: >-
we suggest that this Ras-GTPase cycle involves the ra12 gene
product, another positive regulator of Ras1 whose homologs have not
been identified in other organisms, which could function either as a
second GDP-GTP-exchanging protein or as a factor that negatively
regulates Gap1 activity.
- reference_id: file:SCHPO/ral2/ral2-deep-research-falcon.md
supporting_text: |-
Suppressor analyses and epistasis tests indicate that **gap1 null can bypass the requirement for ral2** to maintain Ras in a GTP-bound state, consistent with ral2 acting to promote Ras1 activity in opposition to Gap1.
core_functions:
- description: >-
Functions as a signaling adaptor upstream of Ras1 in the
Ras1-Scd1-Cdc42 pathway, required for mating pheromone response and
conjugation
directly_involved_in:
- id: GO:0032005
label: signal transduction involved in positive regulation of conjugation
with cellular fusion
locations:
- id: GO:0005783
label: endoplasmic reticulum
- description: >-
Required for maintenance of elongated (rod-shaped) cell morphology
through the Ras1-Scd1-Cdc42 cell polarity pathway; loss results in
spherical cells
directly_involved_in:
- id: GO:0022604
label: regulation of cell morphogenesis
supported_by:
- reference_id: PMID:2586528
supporting_text: >-
The disruptants showed the same phenotype as the original ral2
isolates, i.e., they had spherical cells, had no detectable mating
activity, and exhibited no response to the mating pheromone, but
their vegetative growth was apparently normal.
references:
- id: GO_REF:0000015
title: Use of the ND evidence code for Gene Ontology (GO) terms
findings: []
- id: GO_REF:0000033
title: Annotation inferences using phylogenetic trees
findings:
- statement: >-
IBA annotations for ral2 are based on PANTHER family PTHR43503
(Peroxiredoxin family, Prx6 subfamily), which appears to be an
incorrect family assignment for this kelch repeat protein.
supporting_text: >-
Ral2 contains Kelch-type beta propeller and SKP1/BTB/POZ superfamily
domains, not peroxiredoxin/thioredoxin domains.
- id: GO_REF:0000108
title: >-
Automatic assignment of GO terms using logical inference, based on
inter-ontology links
findings: []
- id: PMID:16823372
title: >-
ORFeome cloning and global analysis of protein localization in the
fission yeast Schizosaccharomyces pombe.
findings:
- statement: >-
Ral2 localizes to the endoplasmic reticulum based on high-throughput
YFP-tagging localization study.
supporting_text: >-
we determined the localization of 4,431 proteins, corresponding to
approximately 90% of the fission yeast proteome, by tagging each ORF
with the yellow fluorescent protein.
- id: PMID:2586528
title: >-
Characterization of the Schizosaccharomyces pombe ral2 gene implicated
in activation of the ras1 gene product.
findings:
- statement: >-
Ral2 encodes a 611 AA protein essential for mating and cell
morphology, functioning upstream of Ras1.
supporting_text: >-
Mutations in the Schizosaccharomyces pombe ral2 gene cause a
phenotype indistinguishable from that of the ras1-defective mutant.
- statement: >-
Ral2 gene product is involved in activation of the Ras1 protein.
supporting_text: >-
These results suggest that the ral2 and ras1 gene products interact
intimately and that the ral2 gene product is involved in activation
of the ras1 protein in S. pombe.
- id: PMID:3071741
title: >-
Isolation and characterization of Schizosaccharomyces pombe mutants
phenotypically similar to ras1-.
findings:
- statement: >-
Ral2 was identified in a screen for mutants phenocopying ras1
deletion, and epistasis analysis places ral1, ral2, ras1 in a common
pathway.
supporting_text: >-
These results suggest that the ral1, ral2 and ras1 genes may
function in a common pathway in that order.
- id: PMID:18257517
title: Phosphoproteome analysis of fission yeast.
findings:
- statement: Ral2 is phosphorylated at Ser-604.
supporting_text: >-
2887 distinct phosphorylation sites were identified from 1194
proteins with an estimated false-discovery rate of <0.5% at the
peptide level.
- id: PMID:2038319
title: >-
Identification of a GTPase-activating protein homolog in
Schizosaccharomyces pombe.
findings:
- statement: >-
The Ras-GTPase cycle in S. pombe involves the ral2 gene product as a
positive regulator of Ras1, proposed to act either as a GDP-GTP
exchange factor or as a negative regulator of the Gap1 GTPase-
activating protein. Gap1 and Ste6 play antagonistic roles in this
cycle.
supporting_text: >-
we suggest that this Ras-GTPase cycle involves the ra12 gene product,
another positive regulator of Ras1 whose homologs have not been
identified in other organisms, which could function either as a second
GDP-GTP-exchanging protein or as a factor that negatively regulates
Gap1 activity.
reference_section_type: ABSTRACT
- id: file:SCHPO/ral2/ral2-deep-research-falcon.md
title: >-
Falcon (Edison Scientific) deep research report on S. pombe ral2
(P15258 / SPBC21.05c).
findings:
- statement: |-
Across independent fission-yeast genetics studies, ral2 is most consistently supported as a positive regulator of Ras1 signaling, functioning in Ras1-dependent control of mating competence and cell shape/polarized growth.
supporting_text: |-
Across independent fission-yeast genetics studies, ral2 is most consistently supported as a **positive regulator of Ras1 signaling** (a “putative activator of Ras1”), functioning in Ras1-dependent control of mating competence and cell shape/polarized growth.
reference_section_type: OTHER
- statement: |-
Genetic epistasis places ral2 in the Ras-GTPase cycle: gap1 null bypasses the requirement for ral2 to keep Ras GTP-bound, and activating point mutations in the ras1 ORF suppress ral2 defects, supporting ral2 acting on Ras1 activation rather than on ras1 expression.
supporting_text: |-
Point mutations in the **ras1 ORF** can suppress ral2 defects, supporting the idea that ral2 acts upstream of or on Ras1 activation rather than simply affecting ras1 expression.
reference_section_type: OTHER
- statement: |-
ral2 is mechanistically framed as a positive regulator of Ras1 whose exact biochemistry was unresolved, hypothesized to be either a GDP->GTP exchange-type activator for Ras1 or an indirect negative regulator of the Ras1 GAP Gap1.
supporting_text: |-
ral2 is treated as a **positive regulator of Ras1** whose mechanism was unresolved: the ral2 product was hypothesized either to function as a **GDP→GTP exchange-type activator** for Ras1 or to act indirectly by **negatively regulating the Ras1 GAP Gap1**, thereby increasing Ras1-GTP.
reference_section_type: OTHER
- statement: |-
S. pombe Ral2 is reported to contain three Kelch repeats at its N-terminus and is placed in the Ras1-Scd pathway; Kelch repeats are protein-protein interaction modules, consistent with an adaptor/scaffold role rather than a defined catalytic activity.
supporting_text: |-
describe *S. pombe* Ral2 as containing **three Kelch repeats at its N-terminus**, and place it in the **Ras1–Scd pathway**.
reference_section_type: OTHER
- statement: |-
A 2024 review of sexual differentiation initiation in S. pombe continues to classify ral2 as a Ras1-Scd pathway protein, reflecting ongoing recognition of ral2 as a Ras-pathway component.
supporting_text: |-
ral2 is included as a “Ras1–Scd pathway protein” in a curated pathway table, reflecting continued recognition of ral2 as a Ras-pathway component in modern syntheses of mating control.
reference_section_type: OTHER
- statement: |-
No direct subcellular localization evidence (e.g., microscopy) for S. pombe Ral2 was retrieved; the available primary literature supports genetic/pathway placement and domain-level inference, so the high-throughput ER localization should be treated cautiously.
supporting_text: |-
No direct subcellular localization evidence for *S. pombe* Ral2 (e.g., microscopy localization) was retrieved in the accessible texts used here; the available sources primarily provide genetic/pathway placement and domain-level inference.
reference_section_type: OTHER
suggested_questions:
- question: >-
What is the precise molecular function of ral2? Does it act as a
scaffold bringing Ras1 together with its GEF, or does it have a
different biochemical activity?
- question: >-
Is the ER localization from the high-throughput study accurate, and
if so, does ral2 function at the ER membrane to facilitate Ras1
activation at endomembranes?
- question: >-
What is the significance of Ser-604 phosphorylation? Is it
regulatory, and which kinase is responsible?
- question: >-
Should the PANTHER family assignment (PTHR43503, Peroxiredoxin Prx6
subfamily) for ral2 be corrected? The protein has kelch repeats, not
peroxiredoxin domains.
- question: >-
Does ral2 interact directly with Ras1 protein, or does it act
indirectly through other pathway components?
suggested_experiments:
- description: >-
Co-immunoprecipitation or yeast two-hybrid assays to test for direct
physical interaction between ral2 and ras1, and between ral2 and
known pathway components (scd1, gef1, skp1).
- description: >-
Structure-function analysis of ral2 kelch repeats by mutagenesis to
determine which protein-protein interactions are essential for mating
and morphology functions.
- description: >-
Live-cell imaging of fluorescently tagged ral2 to confirm ER
localization and determine if it colocalizes with Ras1 at specific
membrane compartments.
- description: >-
Phospho-mutant analysis (S604A, S604D) to determine if Ser-604
phosphorylation regulates ral2 function in mating or morphology.