Fus3 (YBL016W) is the mating-pheromone-response mitogen-activated protein kinase of Saccharomyces cerevisiae, a CMGC-family Ser/Thr kinase that forms the MAPK tier of the Ste11 (MAPKKK) -> Ste7 (MAPKK) -> Fus3 cascade assembled on the Ste5 scaffold. Pheromone binding to the Ste2/Ste3 receptors releases Gbetagamma, which recruits Ste5 to the plasma membrane; there Ste7 dually phosphorylates Fus3 on Thr180 and Tyr182 of its TEY activation loop, a reaction that Ste5 specifically unlocks, making Fus3 activation selective for the mating pathway. Active Fus3 forms a gradient from the tip of the mating projection and shuttles into the nucleus. It phosphorylates the Ste12 repressors Dig1/Dig2 and Ste12 to induce mating genes, the CDK inhibitor Far1 to impose G1 arrest, Fus2 to promote its nuclear export before cell fusion, and the filamentation transcription factor Tec1, triggering its SCF-dependent degradation. Through Tec1 destruction and restraint of Kss1 activation, Fus3 insulates the mating response from the filamentous/invasive growth pathway, and it provides negative feedback on the cascade through phosphorylation of Ste5. Fus3 also restrains Ty1 retrotransposition. Its paralog Kss1 can partially substitute for Fus3 in mating-gene induction but mainly drives filamentous growth. Other Fus3 substrates include the formin Bni1, whose Fus3-dependent phosphorylation and localisation promote polarisation of the mating projection and cell fusion, and the RGS protein Sst2, whose pheromone-induced phosphorylation on Ser539 slows its degradation as part of feedback on G-protein signalling.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000749 response to pheromone triggering conjugation with cellular fusion | IDA PMID:15620357 Pheromone-dependent destruction of the Tec1 transcription fa... | ACCEPT | Summary: Bao et al. showed pheromone signalling induces Fus3-dependent, kinase-activity-dependent degradation of Tec1; Fus3 is the mating-specific MAPK of the pheromone response. Reason: Fus3 is the terminal kinase of the pheromone response pathway and directly executes pheromone-triggered outputs (Ste12/Dig1/Dig2 regulation, Far1-mediated G1 arrest, Tec1 destruction, Fus2 export). Annotation to the response-to-pheromone process is correct and core. Supporting Evidence: PMID:15620357 active Fus3 phosphorylates Tec1 on T273 in vitro PMID:15620357 The mating-specific MAPK, Fus3, prevents crosstalk between the two pathways by unknown mechanisms PMID:8334305 These data support a model in which FUS3 mediates transcription and G1 arrest by direct activation of STE12 and FAR1 |
| GO:0000749 response to pheromone triggering conjugation with cellular fusion | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA machine-learning IEA for response to pheromone triggering conjugation with cellular fusion. Reason: Consistent with extensive experimental evidence that Fus3 is the mating pheromone MAPK (PMID:8334305, PMID:15620357). Supporting Evidence: PMID:8334305 These data support a model in which FUS3 mediates transcription and G1 arrest by direct activation of STE12 and FAR1 file:yeast/FUS3/FUS3-uniprot.txt FUS3 phosphorylates STE7, STE5, FAR1, DIG1, DIG2 and STE12 file:yeast/FUS3/FUS3-deep-research-falcon.md Its primary function is to convert pheromone-receptor activation into coordinated phosphorylation of nuclear, cytoplasmic, and cortical proteins. |
| GO:0001403 invasive growth in response to glucose limitation | IEA GO_REF:0000117 | MODIFY | Summary: ARBA IEA assigning invasive growth in response to glucose limitation, presumably propagated from the Fus3/Kss1 group. Reason: Fus3 does not drive haploid invasive growth; it restrains it. Fus3 kinase activity blocks cross-activation of invasive-growth gene expression by the pheromone cascade (PMID:10652102), and Fus3 phosphorylates Tec1 to trigger its pheromone-induced destruction, so fus3 deletion causes erroneous invasive growth (PMID:15620357). The mutant phenotype is therefore evidence for negative regulation, and the positive process term misrepresents the direction of Fus3's role. The appropriate term is GO:2000218 negative regulation of invasive growth in response to glucose limitation (the same replacement is used for the paralog KSS1 review's repressive role). Propagation Review Root cause: PROPAGATION BAD Failure modes: REGULATORY SIGN INVERSION WRONG ORTHOLOG OR PARALOG Sources checked: ARBA:ARBA00090378 SUPPORTS SOURCE BUT NOT TARGET The ARBA positive invasive-growth transfer follows Kss1-like filamentation biology; Fus3 phosphorylates Tec1 and limits Kss1/crosstalk, so the supported FUS3 process is negative regulation. Proposed replacements: negative regulation of invasive growth in response to glucose limitation Supporting Evidence: PMID:10652102 Fus3 also inhibits haploid invasive growth by blocking cross-activation of invasive growth gene expression by the pheromone response signal cascade PMID:15620357 deletion of FUS3, or deletion of DIA2 results in a loss of signaling specificity such that pheromone pathway signaling erroneously activates filamentation pathway gene expression and invasive growth |
| GO:0001403 invasive growth in response to glucose limitation | IMP PMID:10652102 Fus3 controls Ty1 transpositional dormancy through the invas... | MODIFY | Summary: Conte and Curcio showed that Fus3 kinase activity and dosage inhibit haploid invasive growth; fus3-K42R fails to inhibit invasive growth. Reason: Fus3 does not drive haploid invasive growth; it restrains it. Fus3 kinase activity blocks cross-activation of invasive-growth gene expression by the pheromone cascade (PMID:10652102), and Fus3 phosphorylates Tec1 to trigger its pheromone-induced destruction, so fus3 deletion causes erroneous invasive growth (PMID:15620357). The mutant phenotype is therefore evidence for negative regulation, and the positive process term misrepresents the direction of Fus3's role. The appropriate term is GO:2000218 negative regulation of invasive growth in response to glucose limitation (the same replacement is used for the paralog KSS1 review's repressive role). Proposed replacements: negative regulation of invasive growth in response to glucose limitation Supporting Evidence: PMID:10652102 Fus3 also inhibits haploid invasive growth by blocking cross-activation of invasive growth gene expression by the pheromone response signal cascade PMID:10652102 A chromosomal copy of the kinase-defective fus3-K42R allele fails to inhibit either Ty1 transposition or invasive growth |
| GO:0001403 invasive growth in response to glucose limitation | IMP PMID:15620357 Pheromone-dependent destruction of the Tec1 transcription fa... | MODIFY | Summary: Deletion of FUS3 causes pheromone signalling to erroneously activate filamentation genes and invasive growth, due to loss of Fus3-dependent Tec1 degradation. Reason: Fus3 does not drive haploid invasive growth; it restrains it. Fus3 kinase activity blocks cross-activation of invasive-growth gene expression by the pheromone cascade (PMID:10652102), and Fus3 phosphorylates Tec1 to trigger its pheromone-induced destruction, so fus3 deletion causes erroneous invasive growth (PMID:15620357). The mutant phenotype is therefore evidence for negative regulation, and the positive process term misrepresents the direction of Fus3's role. The appropriate term is GO:2000218 negative regulation of invasive growth in response to glucose limitation (the same replacement is used for the paralog KSS1 review's repressive role). Proposed replacements: negative regulation of invasive growth in response to glucose limitation Supporting Evidence: PMID:15620357 deletion of FUS3, or deletion of DIA2 results in a loss of signaling specificity such that pheromone pathway signaling erroneously activates filamentation pathway gene expression and invasive growth PMID:15620357 active Fus3 phosphorylates Tec1 on T273 in vitro |
| GO:0001403 invasive growth in response to glucose limitation | IMP PMID:8001818 Elements of a single MAP kinase cascade in Saccharomyces cer... | MODIFY | Summary: Roberts and Fink described haploid invasive growth and its dependence on the STE20/STE11/STE7/STE12 kinase cascade; the FUS3 mutant phenotype is presumably reported in the full text (abstract-only in cache). Reason: Fus3 does not drive haploid invasive growth; it restrains it. Fus3 kinase activity blocks cross-activation of invasive-growth gene expression by the pheromone cascade (PMID:10652102), and Fus3 phosphorylates Tec1 to trigger its pheromone-induced destruction, so fus3 deletion causes erroneous invasive growth (PMID:15620357). The mutant phenotype is therefore evidence for negative regulation, and the positive process term misrepresents the direction of Fus3's role. The appropriate term is GO:2000218 negative regulation of invasive growth in response to glucose limitation (the same replacement is used for the paralog KSS1 review's repressive role). The cached abstract does not describe the fus3 phenotype, so the direction is taken from the later mechanistic literature; the IMP itself is not disputed, only the choice of the positive process term. Proposed replacements: negative regulation of invasive growth in response to glucose limitation Supporting Evidence: PMID:8001818 the same components of the MAP kinase cascade necessary for diploid pseudohyphal development (STE20, STE11, STE7, and STE12) are also required for both filament formation and agar penetration in haploids PMID:10652102 Fus3 also inhibits haploid invasive growth by blocking cross-activation of invasive growth gene expression by the pheromone response signal cascade PMID:9393860 Fus3 has a different inhibitory activity that prevents the inappropriate activation of invasion by the pheromone response pathway |
| GO:0004672 protein kinase activity | HDA PMID:16319894 Global analysis of protein phosphorylation in yeast. | ACCEPT | Summary: Proteome-chip in vitro kinase screen (Ptacek et al.) detected Fus3 protein kinase activity on many substrates. Reason: Correct but general; Fus3 is a bona fide Ser/Thr MAP kinase. The more specific GO:0004707 MAP kinase activity is also annotated. Supporting Evidence: PMID:16319894 we identified over 4,000 phosphorylation events involving 1,325 different proteins PMID:8384702 STE7 is a dual-specificity kinase that modifies FUS3 at the appropriate sites and stimulates its catalytic activity in vitro |
| GO:0004672 protein kinase activity | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO IEA from the Ser/Thr kinase active-site signature. Reason: Correct, if general; Fus3 has a canonical protein kinase domain and is catalytically active (MAP kinase activity annotated more specifically). Supporting Evidence: file:yeast/FUS3/FUS3-uniprot.txt Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. MAP kinase subfamily. |
| GO:0004674 protein serine/threonine kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for protein serine/threonine kinase activity across the MAPK family. Reason: Fus3 is a CMGC Ser/Thr MAPK; the IBA is phylogenetically sound and consistent with experimental data. GO:0004707 is the more specific term. Supporting Evidence: file:yeast/FUS3/FUS3-uniprot.txt Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. MAP kinase subfamily. PMID:15620357 active Fus3 phosphorylates Tec1 on T273 in vitro |
| GO:0004707 MAP kinase activity | IDA PMID:15620357 Pheromone-dependent destruction of the Tec1 transcription fa... | ACCEPT | Summary: Active Fus3 phosphorylates Tec1 on T273 in vitro; Tec1 degradation requires Fus3 kinase activity. Reason: Direct demonstration of MAPK phosphorylation of a physiological substrate by pheromone-activated Fus3. This is the core molecular function (MAPK tier of the Ste11-Ste7-Fus3 cascade). Supporting Evidence: PMID:15620357 active Fus3 phosphorylates Tec1 on T273 in vitro PMID:15620357 Degradation requires Fus3 kinase activity and a MAPK phosphorylation site in Tec1 at threonine 273. |
| GO:0004707 MAP kinase activity | IDA PMID:8384702 MAP kinase-related FUS3 from S. cerevisiae is activated by S... | ACCEPT | Summary: Errede et al. showed Ste7 dual-phosphorylates Fus3 at the activating sites and stimulates Fus3 catalytic activity in vitro. Reason: Establishes Fus3 as a MAPK activated by its MAPKK Ste7; core molecular function. Supporting Evidence: PMID:8384702 STE7 is a dual-specificity kinase that modifies FUS3 at the appropriate sites and stimulates its catalytic activity in vitro PMID:1628831 this modification occurs at two amino acids of FUS3, threonine-180 and tyrosine-182 |
| GO:0004707 MAP kinase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined automated IEA for MAP kinase activity. Reason: Correct; matches experimental evidence (PMID:8384702, PMID:15620357). Supporting Evidence: file:yeast/FUS3/FUS3-uniprot.txt Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. MAP kinase subfamily. PMID:8384702 STE7 is a dual-specificity kinase that modifies FUS3 at the appropriate sites and stimulates its catalytic activity in vitro |
| GO:0005515 protein binding | IPI PMID:15020407 Fus1p interacts with components of the Hog1p mitogen-activat... | MODIFY | Summary: Fus3 interaction with the MAPKK Ste7 (PMID:15020407). Reason: Bare protein binding is uninformative. Ste7 is the MAPKK that dually phosphorylates Fus3 on Thr180/Tyr182, and Fus3 forms a specific, high-affinity docking complex with Ste7 (Kd ~5 nM) that is independent of Ste5 (PMID:8668180). The informative MF is mitogen-activated protein kinase kinase binding (same replacement used in the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase binding Supporting Evidence: PMID:15020407 A two-hybrid matrix containing fusion proteins and pheromone response pathway signaling molecules reveals that Fus1p may participate in a complex network of interactions PMID:8668180 Kss1 and Fus3 could each form a tight complex (Kd of approximately 5 nM) with Ste7 in the absence of any additional yeast proteins |
| GO:0005515 protein binding | IPI PMID:15020407 Fus1p interacts with components of the Hog1p mitogen-activat... | REMOVE | Summary: Two-hybrid matrix interaction between Fus3 and its paralog MAPK Kss1. Reason: Bare protein binding is uninformative, and no functional Fus3-Kss1 heteromeric complex has been characterised; the two MAPKs share docking partners (Ste7, Ste5) that could bridge them. Fus3 restrains Kss1 activation (PMID:11583629) but no direct binding-based mechanism is established. Removal of the generic protein binding row does not mean the reported interaction is false. Supporting Evidence: PMID:15020407 A two-hybrid matrix containing fusion proteins and pheromone response pathway signaling molecules reveals that Fus1p may participate in a complex network of interactions PMID:11583629 active Fus3 limits the extent of Kss1 activation, thereby preventing inappropriate signal crossover |
| GO:0005515 protein binding | IPI PMID:15020407 Fus1p interacts with components of the Hog1p mitogen-activat... | MODIFY | Summary: Fus3 interaction with the MAPKK kinase Ste11 (PMID:15020407). Reason: Bare protein binding is uninformative. Two-hybrid studies repeatedly detected a Fus3-Ste11 interaction; Ste11 is the MAPKKK of the same cascade. The contact may be partly bridged by Ste5/Ste7 in vivo, but the two-hybrid readout supports mitogen-activated protein kinase kinase kinase binding as the informative replacement (consistent with the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase kinase binding Supporting Evidence: PMID:15020407 A two-hybrid matrix containing fusion proteins and pheromone response pathway signaling molecules reveals that Fus1p may participate in a complex network of interactions PMID:7851759 Ste5p, a protein of unknown biochemical function, interacted with protein kinases that operate at each step of the MAP kinase cascade, specifically with Ste11p (an MEKK), Ste7p (an MEK), and Fus3p (a MAP kinase) |
| GO:0005515 protein binding | IPI PMID:15020407 Fus1p interacts with components of the Hog1p mitogen-activat... | MODIFY | Summary: Fus3 interaction with the scaffold protein Ste5 (PMID:15020407). Reason: Bare protein binding is uninformative. Ste5 is the MAPK cascade scaffold that tethers Ste11, Ste7 and Fus3 and allosterically unlocks Fus3 for Ste7 phosphorylation (PMID:19303851); Fus3 binds Ste5 through the Fus3-binding domain (FBD) and the VWA/minimal-scaffold domain. The informative MF for Fus3's side of this interaction is scaffold protein binding. Proposed replacements: scaffold protein binding Supporting Evidence: PMID:15020407 A two-hybrid matrix containing fusion proteins and pheromone response pathway signaling molecules reveals that Fus1p may participate in a complex network of interactions PMID:19303851 We identify and structurally characterize a domain in Ste5 that catalytically unlocks Fus3 for phosphorylation by Ste7 |
| GO:0005515 protein binding | IPI PMID:19303851 The Ste5 scaffold directs mating signaling by catalytically ... | MODIFY | Summary: Fus3 interaction with the MAPKK Ste7 (PMID:19303851). Reason: Bare protein binding is uninformative. Ste7 is the MAPKK that dually phosphorylates Fus3 on Thr180/Tyr182, and Fus3 forms a specific, high-affinity docking complex with Ste7 (Kd ~5 nM) that is independent of Ste5 (PMID:8668180). The informative MF is mitogen-activated protein kinase kinase binding (same replacement used in the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase binding Supporting Evidence: PMID:19303851 we find that Fus3 is an intrinsically poor substrate for Ste7 PMID:19303851 We identify and structurally characterize a domain in Ste5 that catalytically unlocks Fus3 for phosphorylation by Ste7 PMID:8668180 Kss1 and Fus3 could each form a tight complex (Kd of approximately 5 nM) with Ste7 in the absence of any additional yeast proteins |
| GO:0005515 protein binding | IPI PMID:19303851 The Ste5 scaffold directs mating signaling by catalytically ... | MODIFY | Summary: Fus3 interaction with the scaffold protein Ste5 (PMID:19303851). Reason: Bare protein binding is uninformative. Ste5 is the MAPK cascade scaffold that tethers Ste11, Ste7 and Fus3 and allosterically unlocks Fus3 for Ste7 phosphorylation (PMID:19303851); Fus3 binds Ste5 through the Fus3-binding domain (FBD) and the VWA/minimal-scaffold domain. The informative MF for Fus3's side of this interaction is scaffold protein binding. Proposed replacements: scaffold protein binding Supporting Evidence: PMID:19303851 We identify and structurally characterize a domain in Ste5 that catalytically unlocks Fus3 for phosphorylation by Ste7 |
| GO:0005515 protein binding | IPI PMID:20489023 A global protein kinase and phosphatase interaction network ... | MODIFY | Summary: Fus3 interaction with the MAPKK Ste7 (PMID:20489023). Reason: Bare protein binding is uninformative. Ste7 is the MAPKK that dually phosphorylates Fus3 on Thr180/Tyr182, and Fus3 forms a specific, high-affinity docking complex with Ste7 (Kd ~5 nM) that is independent of Ste5 (PMID:8668180). The informative MF is mitogen-activated protein kinase kinase binding (same replacement used in the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase binding Supporting Evidence: PMID:20489023 We identified a kinase and phosphatase interaction (KPI) network of 1844 interactions in budding yeast by mass spectrometric analysis of protein complexes PMID:8668180 Kss1 and Fus3 could each form a tight complex (Kd of approximately 5 nM) with Ste7 in the absence of any additional yeast proteins |
| GO:0005515 protein binding | IPI PMID:20489023 A global protein kinase and phosphatase interaction network ... | REMOVE | Summary: AP-MS kinase/phosphatase interaction network detected Fus3 with Bck2. Reason: Bare protein binding from high-throughput AP-MS with no characterised function for a Fus3-Bck2 association; no informative MF can be derived (consistent with the KSS1 review). Removal of the generic protein binding row does not mean the reported interaction is false. Supporting Evidence: PMID:20489023 We identified a kinase and phosphatase interaction (KPI) network of 1844 interactions in budding yeast by mass spectrometric analysis of protein complexes |
| GO:0005515 protein binding | IPI PMID:23267104 Proteome-wide protein interaction measurements of bacterial ... | REMOVE | Summary: IPI with the mitochondrial inner-membrane translocase subunit Tim12, attributed to a microfluidic interaction study of Streptococcus pneumoniae proteins. Reason: Bare protein binding is uninformative, and a Fus3-Tim12 association has no known functional context (Tim12 is an intermembrane-space TIM22 subunit). The cached text of this bacterial-protein interaction paper does not describe the yeast assay, so no informative MF can be derived. Removal of the generic protein binding row does not mean the reported interaction is false. Supporting Evidence: PMID:23267104 Binary protein--protein interactions in the model organism Streptococcus pneumoniae (TIGR4) are measured with a microfluidic high-throughput assay technology |
| GO:0005515 protein binding | IPI PMID:23953117 Exploitation of latent allostery enables the evolution of ne... | REMOVE | Summary: Interaction of S. cerevisiae Fus3 with the Ste5 ortholog from Vanderwaltozyma polyspora (Kpol_1061p54) in an evolutionary study of Ste5 allosteric activator motifs. Reason: Cross-species (xeno) interaction used to probe latent allostery; not a physiological interaction in S. cerevisiae. The native Fus3-Ste5 interaction from the same paper is captured by the scaffold protein binding replacement. Removal of the generic protein binding row does not mean the reported interaction is false. Supporting Evidence: PMID:23953117 One activator (Ste5-VWA) provides pathway insulation and dates to the divergence of Fus3 from its paralog, Kss1 |
| GO:0005515 protein binding | IPI PMID:23953117 Exploitation of latent allostery enables the evolution of ne... | MODIFY | Summary: Fus3 interaction with the MAPKK Ste7 (PMID:23953117). Reason: Bare protein binding is uninformative. Ste7 is the MAPKK that dually phosphorylates Fus3 on Thr180/Tyr182, and Fus3 forms a specific, high-affinity docking complex with Ste7 (Kd ~5 nM) that is independent of Ste5 (PMID:8668180). The informative MF is mitogen-activated protein kinase kinase binding (same replacement used in the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase binding Supporting Evidence: PMID:23953117 One activator (Ste5-VWA) provides pathway insulation and dates to the divergence of Fus3 from its paralog, Kss1 PMID:8668180 Kss1 and Fus3 could each form a tight complex (Kd of approximately 5 nM) with Ste7 in the absence of any additional yeast proteins |
| GO:0005515 protein binding | IPI PMID:23953117 Exploitation of latent allostery enables the evolution of ne... | MODIFY | Summary: Fus3 interaction with the scaffold protein Ste5 (PMID:23953117). Reason: Bare protein binding is uninformative. Ste5 is the MAPK cascade scaffold that tethers Ste11, Ste7 and Fus3 and allosterically unlocks Fus3 for Ste7 phosphorylation (PMID:19303851); Fus3 binds Ste5 through the Fus3-binding domain (FBD) and the VWA/minimal-scaffold domain. The informative MF for Fus3's side of this interaction is scaffold protein binding. Proposed replacements: scaffold protein binding Supporting Evidence: PMID:23953117 which binds Fus3 and allosterically activates autophosphorylation of the MAP kinase on its activation loop tyrosine PMID:19303851 We identify and structurally characterize a domain in Ste5 that catalytically unlocks Fus3 for phosphorylation by Ste7 |
| GO:0005515 protein binding | IPI PMID:37968396 The social and structural architecture of the yeast protein ... | REMOVE | Summary: Large-scale interactome (Michaelis et al. 2023) detected Fus3 with Kss1. Reason: Bare protein binding from a proteome-wide interaction map; no informative MF can be inferred for a Fus3-Kss1 association, which is plausibly bridged by shared cascade components. Removal of the generic protein binding row does not mean the reported interaction is false. Supporting Evidence: PMID:37968396 The 4,159 pull-downs generated a highly structured network of 3,927 proteins connected by 31,004 interactions |
| GO:0005515 protein binding | IPI PMID:7851759 Protein-protein interactions in the yeast pheromone response... | MODIFY | Summary: Fus3 interaction with the MAPKK Ste7 (PMID:7851759). Reason: Bare protein binding is uninformative. Ste7 is the MAPKK that dually phosphorylates Fus3 on Thr180/Tyr182, and Fus3 forms a specific, high-affinity docking complex with Ste7 (Kd ~5 nM) that is independent of Ste5 (PMID:8668180). The informative MF is mitogen-activated protein kinase kinase binding (same replacement used in the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase binding Supporting Evidence: PMID:7851759 We also found that both Ste11p and Ste7p interact with Fus3p and Kss1p PMID:8668180 Kss1 and Fus3 could each form a tight complex (Kd of approximately 5 nM) with Ste7 in the absence of any additional yeast proteins |
| GO:0005515 protein binding | IPI PMID:7851759 Protein-protein interactions in the yeast pheromone response... | MODIFY | Summary: Fus3 interaction with the MAPKK kinase Ste11 (PMID:7851759). Reason: Bare protein binding is uninformative. Two-hybrid studies repeatedly detected a Fus3-Ste11 interaction; Ste11 is the MAPKKK of the same cascade. The contact may be partly bridged by Ste5/Ste7 in vivo, but the two-hybrid readout supports mitogen-activated protein kinase kinase kinase binding as the informative replacement (consistent with the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase kinase binding Supporting Evidence: PMID:7851759 We also found that both Ste11p and Ste7p interact with Fus3p and Kss1p PMID:7851759 Ste5p, a protein of unknown biochemical function, interacted with protein kinases that operate at each step of the MAP kinase cascade, specifically with Ste11p (an MEKK), Ste7p (an MEK), and Fus3p (a MAP kinase) |
| GO:0005515 protein binding | IPI PMID:7851759 Protein-protein interactions in the yeast pheromone response... | MODIFY | Summary: Fus3 interaction with the scaffold protein Ste5 (PMID:7851759). Reason: Bare protein binding is uninformative. Ste5 is the MAPK cascade scaffold that tethers Ste11, Ste7 and Fus3 and allosterically unlocks Fus3 for Ste7 phosphorylation (PMID:19303851); Fus3 binds Ste5 through the Fus3-binding domain (FBD) and the VWA/minimal-scaffold domain. The informative MF for Fus3's side of this interaction is scaffold protein binding. Proposed replacements: scaffold protein binding Supporting Evidence: PMID:7851759 Ste5p, a protein of unknown biochemical function, interacted with protein kinases that operate at each step of the MAP kinase cascade, specifically with Ste11p (an MEKK), Ste7p (an MEK), and Fus3p (a MAP kinase) PMID:19303851 We identify and structurally characterize a domain in Ste5 that catalytically unlocks Fus3 for phosphorylation by Ste7 |
| GO:0005515 protein binding | IPI PMID:8062390 Ste5 tethers multiple protein kinases in the MAP kinase casc... | MODIFY | Summary: Fus3 interaction with the MAPKK Ste7 (PMID:8062390). Reason: Bare protein binding is uninformative. Ste7 is the MAPKK that dually phosphorylates Fus3 on Thr180/Tyr182, and Fus3 forms a specific, high-affinity docking complex with Ste7 (Kd ~5 nM) that is independent of Ste5 (PMID:8668180). The informative MF is mitogen-activated protein kinase kinase binding (same replacement used in the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase binding Supporting Evidence: PMID:8062390 By two-hybrid analysis, Ste11, Ste7, and Fus3 associate with different domains of Ste5 PMID:8668180 Kss1 and Fus3 could each form a tight complex (Kd of approximately 5 nM) with Ste7 in the absence of any additional yeast proteins |
| GO:0005515 protein binding | IPI PMID:8062390 Ste5 tethers multiple protein kinases in the MAP kinase casc... | MODIFY | Summary: Fus3 interaction with the MAPKK kinase Ste11 (PMID:8062390). Reason: Bare protein binding is uninformative. Two-hybrid studies repeatedly detected a Fus3-Ste11 interaction; Ste11 is the MAPKKK of the same cascade. The contact may be partly bridged by Ste5/Ste7 in vivo, but the two-hybrid readout supports mitogen-activated protein kinase kinase kinase binding as the informative replacement (consistent with the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase kinase binding Supporting Evidence: PMID:8062390 Ste5 copurifies with Ste11, Fus3, and a hypophosphorylated form of Ste7 PMID:7851759 Ste5p, a protein of unknown biochemical function, interacted with protein kinases that operate at each step of the MAP kinase cascade, specifically with Ste11p (an MEKK), Ste7p (an MEK), and Fus3p (a MAP kinase) |
| GO:0005515 protein binding | IPI PMID:8062390 Ste5 tethers multiple protein kinases in the MAP kinase casc... | MODIFY | Summary: Fus3 interaction with the scaffold protein Ste5 (PMID:8062390). Reason: Bare protein binding is uninformative. Ste5 is the MAPK cascade scaffold that tethers Ste11, Ste7 and Fus3 and allosterically unlocks Fus3 for Ste7 phosphorylation (PMID:19303851); Fus3 binds Ste5 through the Fus3-binding domain (FBD) and the VWA/minimal-scaffold domain. The informative MF for Fus3's side of this interaction is scaffold protein binding. Proposed replacements: scaffold protein binding Supporting Evidence: PMID:8062390 By two-hybrid analysis, Ste11, Ste7, and Fus3 associate with different domains of Ste5 PMID:8062390 Ste5 copurifies with Ste11, Fus3, and a hypophosphorylated form of Ste7 PMID:19303851 We identify and structurally characterize a domain in Ste5 that catalytically unlocks Fus3 for phosphorylation by Ste7 |
| GO:0005515 protein binding | IPI PMID:8668180 Signaling in the yeast pheromone response pathway: specific ... | MODIFY | Summary: Fus3 interaction with the MAPKK Ste7 (PMID:8668180). Reason: Bare protein binding is uninformative. Ste7 is the MAPKK that dually phosphorylates Fus3 on Thr180/Tyr182, and Fus3 forms a specific, high-affinity docking complex with Ste7 (Kd ~5 nM) that is independent of Ste5 (PMID:8668180). The informative MF is mitogen-activated protein kinase kinase binding (same replacement used in the KSS1 review). Proposed replacements: mitogen-activated protein kinase kinase binding Supporting Evidence: PMID:8668180 Ste7 phosphorylated Kss1 (or Fus3), and Kss1 (or Fus3) phosphorylated Ste7, in a pheromone-stimulated manner PMID:8668180 Kss1 and Fus3 could each form a tight complex (Kd of approximately 5 nM) with Ste7 in the absence of any additional yeast proteins |
| GO:0005515 protein binding | IPI PMID:9311911 Ste5 RING-H2 domain: role in Ste4-promoted oligomerization f... | MODIFY | Summary: Fus3 interaction with the scaffold protein Ste5 (PMID:9311911). Reason: Bare protein binding is uninformative. Ste5 is the MAPK cascade scaffold that tethers Ste11, Ste7 and Fus3 and allosterically unlocks Fus3 for Ste7 phosphorylation (PMID:19303851); Fus3 binds Ste5 through the Fus3-binding domain (FBD) and the VWA/minimal-scaffold domain. The informative MF for Fus3's side of this interaction is scaffold protein binding. Proposed replacements: scaffold protein binding Supporting Evidence: PMID:9311911 In vitro Ste5(C177A C180A) bound each component of the MAPK cascade, but not Ste4 PMID:19303851 We identify and structurally characterize a domain in Ste5 that catalytically unlocks Fus3 for phosphorylation by Ste7 |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO IEA for ATP binding from the protein kinase domain. Reason: Fus3 is an ATP-dependent kinase with a conserved Lys42 whose mutation (K42R) abolishes kinase function. Supporting Evidence: PMID:10652102 A chromosomal copy of the kinase-defective fus3-K42R allele fails to inhibit either Ty1 transposition or invasive growth |
| GO:0005634 nucleus | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for nucleus (is_active_in) across MAPKs. Reason: Fus3 shuttles between cytoplasm and nucleus and active Fus3 translocates to the nucleus to regulate Ste12/Dig1/Dig2 and Tec1. Supporting Evidence: PMID:11781566 Fus3p rapidly shuttles between the nucleus and the cytoplasm independently of pheromones PMID:11781566 activated Fus3p, which dissociates from Ste5p and translocates to the nucleus |
| GO:0005634 nucleus | IDA PMID:10233162 Characterization of Fus3 localization: active Fus3 localizes... | ACCEPT | Summary: Immunofluorescence localises Fus3 throughout cytoplasm and nucleus, slightly enriched in nucleus after pheromone. Reason: Direct localisation evidence; nuclear Fus3 regulates mating transcription. Supporting Evidence: PMID:10233162 By indirect immunofluorescence, Fus3 localizes in punctate spots throughout the cytoplasm and nucleus, with slightly enhanced nuclear localization after pheromone stimulation. |
| GO:0005634 nucleus | IDA PMID:18417610 Analysis of the yeast kinome reveals a network of regulated ... | ACCEPT | Summary: Kinome-wide YFP localisation: Fus3 shifts to the nucleus during filamentous growth. Reason: Direct localisation evidence consistent with other studies. Supporting Evidence: PMID:18417610 The proteins Bcy1p, Fus3p, Ksp1p, Kss1p, Sks1p, and Tpk2p distributed evenly over the cell under conditions of vegetative growth, but they localized predominantly to the nucleus during filamentous growth. |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular location mapping (Nucleus). Reason: Consistent with experimental localisation data. Supporting Evidence: PMID:11781566 Ste5p and Fus3p were found in the nucleus and the cytoplasm |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for cytoplasm (is_active_in). Reason: Fus3 is activated in cytoplasmic/cortical Ste5 complexes and phosphorylates cytoplasmic substrates (Far1 at the cortex, Fus2). Supporting Evidence: PMID:11781566 Ste5p and Fus3p were found in the nucleus and the cytoplasm PMID:10233162 Fus3 has highest specific activity within a 350- to 500-kDa complex previously shown to contain Ste5, Ste11, and Ste7. |
| GO:0005737 cytoplasm | IDA PMID:10233162 Characterization of Fus3 localization: active Fus3 localizes... | ACCEPT | Summary: Immunofluorescence shows Fus3 in punctate cytoplasmic spots and nucleus. Reason: Direct localisation evidence. Supporting Evidence: PMID:10233162 By indirect immunofluorescence, Fus3 localizes in punctate spots throughout the cytoplasm and nucleus, with slightly enhanced nuclear localization after pheromone stimulation. |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular location mapping (Cytoplasm). Reason: Consistent with experimental localisation data. Supporting Evidence: PMID:11781566 Ste5p and Fus3p were found in the nucleus and the cytoplasm |
| GO:0005739 mitochondrion | HDA PMID:14576278 The proteome of Saccharomyces cerevisiae mitochondria. | MARK AS OVER ANNOTATED | Summary: Detection in a high-throughput mass-spectrometric mitochondrial proteome. Reason: Fus3 is an abundant soluble cytoplasmic/nuclear kinase with no mitochondrial targeting signal and no mitochondrial function; identification in purified-organelle proteomics most likely reflects co-purifying contamination. Not supported by any targeted localisation study. Supporting Evidence: PMID:14576278 From >20 million MS spectra, 750 different proteins were identified PMID:11781566 Ste5p and Fus3p were found in the nucleus and the cytoplasm |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | MARK AS OVER ANNOTATED | Summary: Detection in the PROMITO multidimensional mitochondrial proteome. Reason: As for PMID:14576278: proteomic detection without targeted confirmation or functional rationale; likely contaminant. Supporting Evidence: PMID:16823961 A total of 851 different proteins (PROMITO dataset) were identified PMID:11781566 Ste5p and Fus3p were found in the nucleus and the cytoplasm |
| GO:0010494 cytoplasmic stress granule | HDA PMID:26777405 ATPase-Modulated Stress Granules Contain a Diverse Proteome ... | KEEP AS NON CORE | Summary: Identification in purified yeast stress granule cores by mass spectrometry. Reason: High-throughput proteomic localisation under stress; plausible for a cytoplasmic kinase but with no known functional consequence for mating signalling. Kept as non-core (consistent with treatment of other pathway kinases such as PBS2). Supporting Evidence: PMID:26777405 Mass spectroscopy of purified yeast and mammalian stress granule cores identified new components of stress granules |
| GO:0010526 transposable element silencing | IMP PMID:9566871 Posttranslational regulation of Ty1 retrotransposition by mi... | KEEP AS NON CORE | Summary: Fus3, activated at basal levels through the pheromone pathway, post-translationally suppresses Ty1 retrotransposition by destabilising virus-like particle proteins. Reason: Solid genetic evidence that Fus3 kinase activity limits Ty1 transposition, but it acts post-translationally and indirectly (via inhibition of the invasive growth pathway, PMID:10652102), so the fit to 'transposable element silencing' (decreased TE expression) is loose. The regulation-of-transposition terms are obsolete, so this is the closest available term; kept as a non-core, pleiotropic output. Supporting Evidence: PMID:9566871 These findings suggest that Fus3 suppresses Ty1 transposition by destabilizing viruslike particle-associated proteins. PMID:9566871 We demonstrate that suppression of Ty1 transposition in naive cells requires basal levels of Fus3 activation. |
| GO:0042597 periplasmic space | IEA GO_REF:0000044 | REMOVE | Summary: UniProt subcellular location 'Periplasm' mapped to periplasmic space. Reason: Fus3 is a soluble intracellular MAP kinase without a signal peptide. The UniProt 'Periplasm' location cites PMID:11781566, which reports nuclear/cytoplasmic Fus3 and Fus3 at the tips of mating projections (cell cortex), not a cell wall-plasma membrane compartment. The mapping is erroneous (same conclusion reached for KSS1). Supporting Evidence: PMID:11781566 Ste5p and Fus3p were found in the nucleus and the cytoplasm PMID:11781566 Ste5p, Ste7p and Fus3p also localized to tips of mating projections in pheromone-treated cells. |
| GO:0042802 identical protein binding | IPI PMID:15020407 Fus1p interacts with components of the Hog1p mitogen-activat... | REMOVE | Summary: Fus3 self-interaction in a two-hybrid matrix. Reason: Identical protein binding is essentially as uninformative as bare protein binding here: there is no evidence that Fus3 homodimerisation is part of its function (unlike some metazoan ERKs), and two-hybrid self-interaction could be bridged by endogenous Ste5. Removal does not assert the interaction is false. Supporting Evidence: PMID:15020407 A two-hybrid matrix containing fusion proteins and pheromone response pathway signaling molecules reveals that Fus1p may participate in a complex network of interactions |
| GO:0042802 identical protein binding | IPI PMID:23953117 Exploitation of latent allostery enables the evolution of ne... | REMOVE | Summary: Fus3-Fus3 interaction reported in the Coyle et al. study of Ste5 allosteric activation of Fus3. Reason: No functional role for Fus3 self-association has been established; the paper concerns Ste5-FBD/VWA allosteric activation of Fus3 autophosphorylation, not Fus3 dimerisation. The generic identical-protein-binding term adds no functional information. Supporting Evidence: PMID:23953117 which binds Fus3 and allosterically activates autophosphorylation of the MAP kinase on its activation loop tyrosine |
| GO:0043332 mating projection tip | IDA PMID:11781566 MAP kinase dynamics in response to pheromones in budding yea... | ACCEPT | Summary: GFP-Fus3 localises to tips of mating projections in pheromone-treated cells, recruited by membrane-bound Ste5. Reason: Direct localisation evidence; the shmoo tip is where Ste5 activates Fus3 and where Fus3 regulates polarised growth. Supporting Evidence: PMID:11781566 Ste5p, Ste7p and Fus3p also localized to tips of mating projections in pheromone-treated cells. PMID:11781566 Membrane-bound Ste5p can specifically recruit Fus3p and Ste7p to the cell cortex. |
| GO:0043332 mating projection tip | IDA PMID:17952059 Spatial regulation of Fus3 MAP kinase activity through a rea... | ACCEPT | Summary: FLIM reveals a gradient of active, dually phosphorylated Fus3 emanating from the mating projection tip. Reason: Supports activation of Fus3 at the projection tip. Supporting Evidence: PMID:17952059 revealed a gradient of Fus3(PP) activity emanating from the tip of the mating projection |
| GO:0043409 negative regulation of MAPK cascade | IPI PMID:16424299 The Ste5 scaffold allosterically modulates signaling output ... | KEEP AS NON CORE | Summary: Ste5 FBD allosterically activates Fus3 autophosphorylation; the resulting partially active Fus3 promotes Ste5 phosphorylation and reduces pathway transcriptional output (negative feedback). Reason: Fus3 itself performs the feedback step (phosphorylating Ste5), so the regulatory annotation is appropriate. Fus3 also limits Kss1 activation (PMID:11583629). Negative feedback tunes the cascade rather than being Fus3's primary signalling function, so kept as non-core. Supporting Evidence: PMID:16424299 autoactivated Fus3 appears to have a negative regulatory role, promoting Ste5 phosphorylation and a decrease in pathway transcriptional output PMID:11583629 active Fus3 limits the extent of Kss1 activation, thereby preventing inappropriate signal crossover |
| GO:0046827 positive regulation of protein export from nucleus | IMP PMID:22588722 A mechanism for the coordination of proliferation and differ... | KEEP AS NON CORE | Summary: Fus3 phosphorylates Fus2 Ser84 to drive Fus2 nuclear export, and down-regulates Ser67 phosphorylation, coupling cell-cycle arrest to cell fusion. Reason: Direct experimental evidence that Fus3 phosphorylates Fus2 to promote its nuclear export; one specific downstream output of Fus3 in preparation for cell fusion rather than the core signalling function. Supporting Evidence: PMID:22588722 In response to pheromone signaling, the mitogen-activated protein kinase Fus3p phosphorylates Ser 84 in Fus2p to drive nuclear export. |
| GO:0071507 pheromone response MAPK cascade | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for pheromone response MAPK cascade, from the fungal Fus3/Spk1 mating-MAPK node PTN001172087. Reason: Fus3 is the defining MAPK of the pheromone response MAPK cascade (the GO definition names Fus3). Core process. Supporting Evidence: PMID:8159759 reconstituted a kinase cascade in which STE11 phosphorylates and activates STE7, which in turn phosphorylates the mitogen-activated protein kinase FUS3 PMID:8384702 STE7 is a dual-specificity kinase that modifies FUS3 at the appropriate sites and stimulates its catalytic activity in vitro |
| GO:0071507 pheromone response MAPK cascade | IDA PMID:8159759 Reconstitution of a yeast protein kinase cascade in vitro: a... | ACCEPT | Summary: In vitro reconstitution of the Ste11 -> Ste7 -> Fus3 kinase cascade with purified GST fusions. Reason: Directly demonstrates Fus3 as the terminal kinase of the pheromone MAPK cascade. Core process. Supporting Evidence: PMID:8159759 reconstituted a kinase cascade in which STE11 phosphorylates and activates STE7, which in turn phosphorylates the mitogen-activated protein kinase FUS3 |
| GO:0106310 protein serine kinase activity | IEA GO_REF:0000116 | ACCEPT | Summary: Rhea-based IEA for protein serine kinase activity (RHEA:17989). Reason: Fus3 phosphorylates serine and threonine residues of its substrates; correct though less specific than MAP kinase activity. Supporting Evidence: file:yeast/FUS3/FUS3-uniprot.txt Reaction=L-seryl-[protein] + ATP = O-phospho-L-seryl-[protein] + ADP + |
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Download this section (compressed HTML)Q: Which Gpa1-associated Fus3 targets mediate polarity-site guidance if not Ste4, Ste18, Far1, or Bni1, and should those direct inputs be captured as has_input on MAP kinase activity in a GO-CAM of the pheromone response?
Q: Is GO:0010526 transposable element silencing the right home for Fus3's post-translational suppression of Ty1 retrotransposition, given that all regulation-of-transposition terms are obsolete?
Q: Should Far1-mediated G1 arrest be annotated to Fus3 as a regulation-of-cell-cycle process, given that Fus3 directly phosphorylates Far1 (the actual CDK inhibitor)?
Experiment: Analog-sensitive fus3 allele combined with quantitative phosphoproteomics after pheromone treatment in a kss1 deletion background, to define the direct Fus3 substrate set and separate it from Kss1-dependent sites.
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Download this section (compressed HTML)Mitogen-activated serine/threonine protein kinase involved in mating; phosphoactivated by Ste7p; substrates include Ste12p, Far1p, Bni1p, Sst2p; inhibits invasive growth during mating by phosphorylating Tec1p, promoting its; inhibits recruitment of Ste5p, Cdc42p-mediated asymmetry and mating morphogenesis
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