Ral2 is a Kelch repeat-containing positive regulator of Ras1 signaling in S. pombe. It acts genetically upstream of Ras1 in pathways controlling mating-pheromone response, conjugation, and polarized cell shape, although its precise biochemical activity remains unknown. Ral2 contains three N-terminal Kelch repeats consistent with a protein-interaction role. Deletion of ral2 phenocopies ras1 deletion, producing spherical cells with no mating activity, while activated Ras1 restores rod-like morphology and pheromone response. Vegetative growth is unaffected by ral2 loss.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| 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 ~44β56 aa motifs occurring in 5β7 repeats in many proteins and commonly forming **Ξ²-propeller structures**, generally functioning as proteinβprotein 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 ... | UNDECIDED | Summary: The ER call comes from a proteome-wide YFP localization screen, but the accessible publication record does not expose the Ral2-specific image or classification. No independent Ral2 localization study was identified in the existing literature review. Reason: The experimental curator call should not be overruled without the gene-specific primary result, but ER cannot be treated as a core functional site from the available abstract-level evidence alone. The is_active_in qualifier is also stronger than localization by itself establishes. 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:0031137 regulation of conjugation with cellular fusion | IBA GO_REF:0000033 | ACCEPT | Summary: Ral2 is required for conjugation and mating-pheromone response, and the PAINT assertion is placed on the Ral2/Mds3-related node PTN005166285. Its source set includes Ral2's own experimental annotation, which is expected target-specific grounding rather than circularity. Reason: The IBA agrees with direct ral2 mutant phenotypes and with genetic placement upstream of Ras1 in the mating pathway. Supporting Evidence: 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. |
| GO:2000784 positive regulation of establishment of cell polarity regulating cell shape | IMP PMID:2586528 Characterization of the Schizosaccharomyces pombe ral2 gene ... | ACCEPT | Summary: Loss of ral2 produces spherical cells, and activated Ras1 restores rod-like morphology, directly supporting a positive role upstream of Ras1 in establishing polarized cell shape. Reason: The mutant and activated-ras1 rescue phenotypes directly support positive regulation of cell polarity governing cell shape. 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. |
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Download this section (compressed HTML)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: Which interaction mediated by the Ral2 Kelch/BTB-like architecture promotes Ras1 activation, and does Ral2 regulate the Ste6 GEF, the Gap1 GAP, or Ras1 through a distinct mechanism?
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.
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