PBS2

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0000165 MAPK cascade	IBA GO_REF:0000033	ACCEPT	Summary: Phylogenetic (PAINT) inference that Pbs2 participates in a MAPK cascade. Reason: Pbs2 is the sole MAPKK of the HOG cascade, sitting between the MAPKKKs Ssk2/Ssk22/Ste11 and the MAPK Hog1. The IBA is correct; GO:0038066 p38MAPK cascade (also annotated) is the more specific descendant. Supporting Evidence: PMID:7681220 Two of these genes, HOG1 and PBS2, encode members of the mitogen-activated protein kinase (MAP kinase) and MAP kinase kinase gene families, respectively. PMID:7624781 Pbs2p was activated by MAP kinase kinase kinases (MAPKKKs) Ssk2p and Ssk22p that are under the control of the SLN1-SSK1 two-component osmosensor.
GO:0004596 protein-N-terminal amino-acid acetyltransferase activity	IMP PMID:12783868 Nat3p and Mdm20p are required for function of yeast NatB Nal...	UNDECIDED	Summary: IMP annotation of N-terminal amino-acid acetyltransferase activity to Pbs2 from a paper characterizing the NatB acetyltransferase (Nat3p/Mdm20p). Reason: Kept as UNDECIDED rather than REMOVE because the cached paper is abstract-only, so this experimental row cannot be checked against the full text; the evidence below strongly suggests a NAT3 mis-attribution. Contradicted on biological grounds. Pbs2 is a STE-family protein kinase with no GNAT/acetyltransferase domain, and the cited abstract states explicitly that NatB consists of Nat3p and Mdm20p. The row is UniProt-assigned (2006); UniProt's own P08018 entry does not mention NatB or this paper, and SGD's current curated PBS2 annotation set does not include it, whereas SGD annotates NAT3 (Q06504) to NatB from this same paper. This looks like an accession mix-up (NAT3 intended). Supporting Evidence: PMID:12783868 NatB is composed of the interacting Nat3p and Mdm20p subunits, both of which are required for acetyltransferase activity. file:yeast/PBS2/PBS2-uniprot.txt Belongs to the protein kinase superfamily. STE Ser/Thr
GO:0004672 protein kinase activity	HDA PMID:16319894 Global analysis of protein phosphorylation in yeast.	ACCEPT	Summary: High-throughput proteome-chip in vitro kinase assay detecting Pbs2 protein kinase activity. Reason: Pbs2 is an active protein kinase; the annotation is correct though general. The informative child term is MAP kinase kinase activity (GO:0004708). Supporting Evidence: PMID:16319894 Here we describe, with the use of proteome chip technology, the in vitro substrates recognized by most yeast protein kinases PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity.
GO:0004672 protein kinase activity	IEA GO_REF:0000002	ACCEPT	Summary: InterPro (Ser/Thr kinase active site) mapping to protein kinase activity. Reason: Pbs2 has a catalytically active eukaryotic protein kinase domain (360-623). Correct, general parent of MAP kinase kinase activity. Supporting Evidence: file:yeast/PBS2/PBS2-uniprot.txt Belongs to the protein kinase superfamily. STE Ser/Thr PMID:7681220 Two of these genes, HOG1 and PBS2, encode members of the mitogen-activated protein kinase (MAP kinase) and MAP kinase kinase gene families, respectively.
GO:0004708 MAP kinase kinase activity	IBA GO_REF:0000033	ACCEPT	Summary: PAINT IBA for MAP kinase kinase activity. Reason: Pbs2 is the MAPKK of the HOG pathway: activated by Ssk2/Ssk22 or Ste11, it dually phosphorylates Hog1 on Thr174/Tyr176. This is the core molecular function. Supporting Evidence: PMID:7681220 Two of these genes, HOG1 and PBS2, encode members of the mitogen-activated protein kinase (MAP kinase) and MAP kinase kinase gene families, respectively. PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity.
GO:0004708 MAP kinase kinase activity	IEA GO_REF:0000120	ACCEPT	Summary: IEA (ARBA/EC 2.7.12.2) for MAP kinase kinase activity. Reason: Pbs2 is the MAPKK of the HOG pathway: activated by Ssk2/Ssk22 or Ste11, it dually phosphorylates Hog1 on Thr174/Tyr176. This is the core molecular function. Supporting Evidence: PMID:7681220 Two of these genes, HOG1 and PBS2, encode members of the mitogen-activated protein kinase (MAP kinase) and MAP kinase kinase gene families, respectively. PMID:38270553 The activity of Hog1p was specifically enhanced at these proline-adjacent sites on Dot1p upon Hog1p activation by the osmostress-responsive MAP kinase kinase PBS2 (Pbs2p).
GO:0004708 MAP kinase kinase activity	IMP PMID:7624781 Activation of yeast PBS2 MAPKK by MAPKKKs or by binding of a...	ACCEPT	Summary: SGD IMP: pbs2 mutants and Pbs2 activation analysis place Pbs2 as the MAPKK activated by Ssk2/Ssk22 or via Sho1. Reason: Pbs2 is the MAPKK of the HOG pathway: activated by Ssk2/Ssk22 or Ste11, it dually phosphorylates Hog1 on Thr174/Tyr176. This is the core molecular function. Supporting Evidence: PMID:7624781 Pbs2p was activated by MAP kinase kinase kinases (MAPKKKs) Ssk2p and Ssk22p that are under the control of the SLN1-SSK1 two-component osmosensor. PMID:7624781 Pbs2p was activated by two independent signals that emanated from distinct cell-surface osmosensors. PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity.
GO:0004708 MAP kinase kinase activity	ISS PMID:7681220 An osmosensing signal transduction pathway in yeast.	ACCEPT	Summary: SGD ISS from mammalian MAP2K1 (P31938) for MAP kinase kinase activity, from the founding HOG paper. Reason: Pbs2 is the MAPKK of the HOG pathway: activated by Ssk2/Ssk22 or Ste11, it dually phosphorylates Hog1 on Thr174/Tyr176. This is the core molecular function. Supporting Evidence: PMID:7681220 Two of these genes, HOG1 and PBS2, encode members of the mitogen-activated protein kinase (MAP kinase) and MAP kinase kinase gene families, respectively. PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity.
GO:0004713 protein tyrosine kinase activity	EXP PMID:38270553 Proline-directed yeast and human MAP kinases phosphorylate t...	ACCEPT	Summary: UniProt EXP: Pbs2 phosphorylates the Hog1 activation-loop tyrosine (Tyr176) in vitro (used to activate Hog1 in Dot1 kinase assays). Reason: Correct: as a dual-specificity MAPKK, Pbs2 phosphorylates Hog1 on Tyr176 (and Thr174). UniProt cites this paper for the tyrosine reaction (RHEA:10596). MAP kinase kinase activity (GO:0004708) is the more informative term for the same activity. Supporting Evidence: PMID:38270553 The activity of Hog1p was specifically enhanced at these proline-adjacent sites on Dot1p upon Hog1p activation by the osmostress-responsive MAP kinase kinase PBS2 (Pbs2p). PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity.
GO:0004713 protein tyrosine kinase activity	IEA GO_REF:0000116	ACCEPT	Summary: Rhea-based IEA for protein tyrosine kinase activity (RHEA:10596). Reason: Consistent with Pbs2 dual-specificity phosphorylation of Hog1 Tyr176; experimentally supported. Supporting Evidence: PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity.
GO:0005078 MAP kinase scaffold activity	IPI PMID:15200958 Protein-protein interaction affinity plays a crucial role in...	ACCEPT	Summary: SGD IPI (with Sho1): Sho1 SH3 affinity for Pbs2 quantitatively controls HOG output, supporting Pbs2 scaffolding at Sho1. Reason: Pbs2 binds the Sho1 osmosensor (through its N-terminal proline-rich motif), the MAPKKK Ste11, and the MAPK Hog1, and together with Sho1 acts as a co-scaffold that directs Ste11 to Pbs2 and insulates HOG signaling from the pheromone pathway. MAP kinase scaffold activity is well supported and is a core function alongside MAPKK activity. Supporting Evidence: PMID:15200958 we engineered a series of mutants that incrementally reduced the affinity of the yeast Sho1p SH3 domain for its in vivo target, the MAP kinase kinase Pbs2p. PMID:15200958 We demonstrate a strong linear correlation between the binding energy of these mutants and quantitative in vivo outputs from the HOG high-osmolarity response pathway controlled by Sho1p. PMID:15200959 In the yeast high osmolarity response pathway, the MAP kinase kinase Pbs2 is thought to function as a scaffold, since it binds the osmosensor Sho1, the upstream MAP kinase kinase kinase Ste11, and the downstream MAP kinase Hog1.
GO:0005078 MAP kinase scaffold activity	IPI PMID:15200959 Sho1 and Pbs2 act as coscaffolds linking components in the y...	ACCEPT	Summary: SGD IPI (with Ste11): Sho1 and Pbs2 act as co-scaffolds linking Ste11 to Pbs2. Reason: Pbs2 binds the Sho1 osmosensor (through its N-terminal proline-rich motif), the MAPKKK Ste11, and the MAPK Hog1, and together with Sho1 acts as a co-scaffold that directs Ste11 to Pbs2 and insulates HOG signaling from the pheromone pathway. MAP kinase scaffold activity is well supported and is a core function alongside MAPKK activity. Supporting Evidence: PMID:15200959 In the yeast high osmolarity response pathway, the MAP kinase kinase Pbs2 is thought to function as a scaffold, since it binds the osmosensor Sho1, the upstream MAP kinase kinase kinase Ste11, and the downstream MAP kinase Hog1. PMID:15200959 Thus, a network of interactions provided by both Sho1 and Pbs2 appears to direct pathway information flow.
GO:0005078 MAP kinase scaffold activity	IPI PMID:9180081 Osmotic activation of the HOG MAPK pathway via Ste11p MAPKKK...	ACCEPT	Summary: SGD IPI (with Sho1): Pbs2 binds Sho1, Ste11 and Hog1 and was proposed to serve as a scaffold. Reason: Pbs2 binds the Sho1 osmosensor (through its N-terminal proline-rich motif), the MAPKKK Ste11, and the MAPK Hog1, and together with Sho1 acts as a co-scaffold that directs Ste11 to Pbs2 and insulates HOG signaling from the pheromone pathway. MAP kinase scaffold activity is well supported and is a core function alongside MAPKK activity. Supporting Evidence: PMID:9180081 The MAPKK Pbs2p bound to the Sho1p osmosensor, the MAPKKK Ste11p, and the MAPK Hog1p. Thus, Pbs2p may serve as a scaffold protein.
GO:0005078 MAP kinase scaffold activity	IPI PMID:9180081 Osmotic activation of the HOG MAPK pathway via Ste11p MAPKKK...	ACCEPT	Summary: SGD IPI (with Hog1): Pbs2 binds Hog1 as part of its scaffold role. Reason: Pbs2 binds the Sho1 osmosensor (through its N-terminal proline-rich motif), the MAPKKK Ste11, and the MAPK Hog1, and together with Sho1 acts as a co-scaffold that directs Ste11 to Pbs2 and insulates HOG signaling from the pheromone pathway. MAP kinase scaffold activity is well supported and is a core function alongside MAPKK activity. Supporting Evidence: PMID:9180081 The MAPKK Pbs2p bound to the Sho1p osmosensor, the MAPKKK Ste11p, and the MAPK Hog1p. Thus, Pbs2p may serve as a scaffold protein. file:yeast/PBS2/PBS2-deep-research-falcon.md Mutating it weakens interaction and Hog1 activation; transferring it to another MAP2K, Ste7, permits Ssk2/Ssk22-dependent phosphorylation of Ste7.
GO:0005078 MAP kinase scaffold activity	IPI PMID:9180081 Osmotic activation of the HOG MAPK pathway via Ste11p MAPKKK...	ACCEPT	Summary: SGD IPI (with Ste11): Pbs2 binds Ste11 as part of its scaffold role. Reason: Pbs2 binds the Sho1 osmosensor (through its N-terminal proline-rich motif), the MAPKKK Ste11, and the MAPK Hog1, and together with Sho1 acts as a co-scaffold that directs Ste11 to Pbs2 and insulates HOG signaling from the pheromone pathway. MAP kinase scaffold activity is well supported and is a core function alongside MAPKK activity. Supporting Evidence: PMID:9180081 The MAPKK Pbs2p bound to the Sho1p osmosensor, the MAPKKK Ste11p, and the MAPK Hog1p. Thus, Pbs2p may serve as a scaffold protein. PMID:9180081 A second osmosensor, Sho1p, also activated Pbs2p and Hog1p, but did so through the Ste11p MAPKKK.
GO:0005515 protein binding	IPI PMID:11743162 A combined experimental and computational strategy to define...	MODIFY	Summary: Large-scale SH3 domain phage-display/two-hybrid network detecting Pbs2 binding to Sho1 (IntAct). Reason: Bare protein binding is uninformative. The Pbs2-Sho1 interaction is mediated by the Pbs2 N-terminal proline-rich motif (PLPPLP) binding the Sho1 SH3 domain, so SH3 domain binding captures the molecular function. Removal of the generic term does not mean the interaction is false. Proposed replacements: SH3 domain binding Supporting Evidence: PMID:11743162 Application to yeast SH3 domains generated a phage-display network containing 394 interactions among 206 proteins and a two-hybrid network containing 233 interactions among 145 proteins. PMID:7624781 Alternatively, Pbs2p was activated by a mechanism that involves the binding of its amino terminal proline-rich motif to the Src homology 3 (SH3) domain of a putative transmembrane osmosensor Sho1p. PMID:14668868 Here we show that an isolated peptide ligand from the yeast protein Pbs2 recognizes its biological partner, the SH3 domain from Sho1, with near-absolute specificity
GO:0005515 protein binding	IPI PMID:11805837 Systematic identification of protein complexes in Saccharomy...	MODIFY	Summary: High-throughput affinity purification/MS co-purification of Pbs2 with Nbp2 (IntAct). Reason: Bare protein binding is uninformative. Pbs2 binds the SH3 domain of Nbp2 through a Pro-rich motif distinct from the Sho1-binding motif; Nbp2 thereby recruits the PP2C Ptc1 to the Pbs2-Hog1 module. SH3 domain binding captures the function. Removal of the generic term does not mean the interaction is false. Proposed replacements: SH3 domain binding Supporting Evidence: PMID:11805837 Beginning with 10% of predicted yeast proteins as baits, we detected 3,617 associated proteins covering 25% of the yeast proteome. PMID:14685261 Furthermore, Nbp2 contained separate binding sites for Ptc1 and Pbs2: the novel N-terminal domain bound Ptc1, while the SH3 domain bound Pbs2. PMID:14685261 In addition, the Pbs2 scaffold bound the Nbp2 SH3 via a Pro-rich motif distinct from that which binds the SH3 domain of the positive regulator Sho1.
GO:0005515 protein binding	IPI PMID:12783868 Nat3p and Mdm20p are required for function of yeast NatB Nal...	UNDECIDED	Summary: UniProt IPI of Pbs2 with Mdm20 (NatB auxiliary subunit) from the NatB characterization paper. Reason: Kept as UNDECIDED rather than REMOVE because the cached paper is abstract-only, so this experimental row cannot be checked against the full text; the evidence below strongly suggests a NAT3 mis-attribution. Generic protein binding is uninformative, and the row is almost certainly mis-attributed: the abstract defines NatB as the Nat3p-Mdm20p pair, UniProt's own P08018 SUBUNIT line lists only NBP2, PTC1, SHO1 and STE11, and SGD does not carry this interaction for PBS2. No informative MF can be derived. Supporting Evidence: PMID:12783868 NatB is composed of the interacting Nat3p and Mdm20p subunits, both of which are required for acetyltransferase activity. file:yeast/PBS2/PBS2-uniprot.txt Interacts with NBP2, PTC1, SHO1 and STE11.
GO:0005515 protein binding	IPI PMID:14668868 Optimization of specificity in a cellular protein interactio...	MODIFY	Summary: Pbs2 SH3-ligand peptide binds the Sho1 SH3 domain with near-absolute specificity among yeast SH3 domains (IntAct). Reason: Bare protein binding is uninformative. The Pbs2-Sho1 interaction is mediated by the Pbs2 N-terminal proline-rich motif (PLPPLP) binding the Sho1 SH3 domain, so SH3 domain binding captures the molecular function. Removal of the generic term does not mean the interaction is false. Proposed replacements: SH3 domain binding Supporting Evidence: PMID:14668868 Here we show that an isolated peptide ligand from the yeast protein Pbs2 recognizes its biological partner, the SH3 domain from Sho1, with near-absolute specificity
GO:0005515 protein binding	IPI PMID:14685261 Nbp2 targets the Ptc1-type 2C Ser/Thr phosphatase to the HOG...	MODIFY	Summary: SGD IPI (with Ptc1, Nbp2): Pbs2 forms a complex with Ptc1 via Nbp2, whose SH3 domain binds a Pbs2 Pro-rich motif. Reason: Bare protein binding is uninformative. The direct contact is between a Pbs2 Pro-rich motif and the Nbp2 SH3 domain; Ptc1 association with Pbs2 requires Nbp2, so phosphatase binding would overstate a direct Pbs2-Ptc1 contact. SH3 domain binding is the informative replacement. Proposed replacements: SH3 domain binding Supporting Evidence: PMID:14685261 Furthermore, Nbp2 contained separate binding sites for Ptc1 and Pbs2: the novel N-terminal domain bound Ptc1, while the SH3 domain bound Pbs2. PMID:14685261 In addition, the Pbs2 scaffold bound the Nbp2 SH3 via a Pro-rich motif distinct from that which binds the SH3 domain of the positive regulator Sho1. PMID:14685261 In this work, we show that the SH3 domain-containing protein Nbp2 negatively regulates Hog1 by recruiting Ptc1 to the Pbs2-Hog1 complex.
GO:0005515 protein binding	IPI PMID:14737190 Protein interaction networks by proteome peptide scanning.	MODIFY	Summary: Proteome peptide scanning of SH3 domain ligands, including Sho1 SH3 binding to Pbs2 (IntAct). Reason: Bare protein binding is uninformative. The Pbs2-Sho1 interaction is mediated by the Pbs2 N-terminal proline-rich motif (PLPPLP) binding the Sho1 SH3 domain, so SH3 domain binding captures the molecular function. Removal of the generic term does not mean the interaction is false. Proposed replacements: SH3 domain binding Supporting Evidence: PMID:14737190 By contrast, the SH3 domain of Sho1 (P40073) and Myo5 (Q04439) were found to bind only to class 1 peptides PMID:14668868 Here we show that an isolated peptide ligand from the yeast protein Pbs2 recognizes its biological partner, the SH3 domain from Sho1, with near-absolute specificity
GO:0005515 protein binding	IPI PMID:19841731 Bayesian modeling of the yeast SH3 domain interactome predic...	MODIFY	Summary: SH3 interactome study (phage display) including the Sho1 SH3-Pbs2 interaction (IntAct). Reason: Bare protein binding is uninformative. The Pbs2-Sho1 interaction is mediated by the Pbs2 N-terminal proline-rich motif (PLPPLP) binding the Sho1 SH3 domain, so SH3 domain binding captures the molecular function. Removal of the generic term does not mean the interaction is false. Proposed replacements: SH3 domain binding Supporting Evidence: PMID:19841731 To assess the accuracy of our phage-derived data for SH3 domains, we examined the SH3 domain of Sho1p PMID:14668868 Here we show that an isolated peptide ligand from the yeast protein Pbs2 recognizes its biological partner, the SH3 domain from Sho1, with near-absolute specificity
GO:0005515 protein binding	IPI PMID:19841731 Bayesian modeling of the yeast SH3 domain interactome predic...	MODIFY	Summary: SH3 interactome study including the Nbp2 SH3-Pbs2 interaction (IntAct). Reason: Bare protein binding is uninformative. Pbs2 binds the SH3 domain of Nbp2 through a Pro-rich motif distinct from the Sho1-binding motif; Nbp2 thereby recruits the PP2C Ptc1 to the Pbs2-Hog1 module. SH3 domain binding captures the function. Removal of the generic term does not mean the interaction is false. Proposed replacements: SH3 domain binding Supporting Evidence: PMID:19841731 To assess the accuracy of our phage-derived data for SH3 domains, we examined the SH3 domain of Sho1p PMID:14685261 Furthermore, Nbp2 contained separate binding sites for Ptc1 and Pbs2: the novel N-terminal domain bound Ptc1, while the SH3 domain bound Pbs2.
GO:0005515 protein binding	IPI PMID:22623719 Sho1p connects the plasma membrane with proteins of the cyto...	MODIFY	Summary: Study of Sho1 SH3-mediated interactions in cytokinesis (HICS complex); Pbs2-Sho1 binding reported (IntAct). Reason: Bare protein binding is uninformative. The Pbs2-Sho1 interaction is mediated by the Pbs2 N-terminal proline-rich motif (PLPPLP) binding the Sho1 SH3 domain, so SH3 domain binding captures the molecular function. Removal of the generic term does not mean the interaction is false. Proposed replacements: SH3 domain binding Supporting Evidence: PMID:22623719 The HICS complex is formed exclusively through interactions between three SH3 domains located in Cyk3p, Hof1p and Sho1p PMID:14668868 Here we show that an isolated peptide ligand from the yeast protein Pbs2 recognizes its biological partner, the SH3 domain from Sho1, with near-absolute specificity
GO:0005515 protein binding	IPI PMID:9180081 Osmotic activation of the HOG MAPK pathway via Ste11p MAPKKK...	MODIFY	Summary: Pbs2 binds the Sho1 osmosensor (IntAct curation of the Posas and Saito scaffold paper). Reason: Bare protein binding is uninformative. The Pbs2-Sho1 interaction is mediated by the Pbs2 N-terminal proline-rich motif (PLPPLP) binding the Sho1 SH3 domain, so SH3 domain binding captures the molecular function. Removal of the generic term does not mean the interaction is false. Proposed replacements: SH3 domain binding Supporting Evidence: PMID:9180081 The MAPKK Pbs2p bound to the Sho1p osmosensor, the MAPKKK Ste11p, and the MAPK Hog1p. Thus, Pbs2p may serve as a scaffold protein. PMID:7624781 Alternatively, Pbs2p was activated by a mechanism that involves the binding of its amino terminal proline-rich motif to the Src homology 3 (SH3) domain of a putative transmembrane osmosensor Sho1p.
GO:0005524 ATP binding	IEA GO_REF:0000002	ACCEPT	Summary: InterPro protein-kinase-domain mapping to ATP binding. Reason: Pbs2 is a catalytically active protein kinase that uses ATP; ATP binding is implied by its kinase activity (UniProt ATP-binding sites 366-374, K389). Supporting Evidence: file:yeast/PBS2/PBS2-uniprot.txt Belongs to the protein kinase superfamily. STE Ser/Thr PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity.
GO:0005737 cytoplasm	IDA PMID:9755161 Regulated nucleo/cytoplasmic exchange of HOG1 MAPK requires ...	ACCEPT	Summary: SGD IDA (is_active_in): Pbs2-GFP localizes to the cytoplasm and does not enter the nucleus upon osmostress. Reason: GFP-tagged Pbs2 is cytoplasmic and excluded from the nucleus before and after osmotic stress; Pbs2 activates Hog1 in the cytoplasm, after which Hog1 enters the nucleus. Supporting Evidence: PMID:9755161 we found that HOG1, PBS2 and STE11 localize to the cytoplasm of unstressed cells. Following osmotic stress, HOG1, but neither PBS2 nor STE11, translocates into the nucleus. PMID:10980703 Pbs2 tagged with green fluorescent protein (Pbs2-GFP) is evenly distributed in the cytoplasm but excluded from the nucleus before and after exposure to stress.
GO:0005737 cytoplasm	IDA PMID:9755161 Regulated nucleo/cytoplasmic exchange of HOG1 MAPK requires ...	ACCEPT	Summary: SGD IDA: Pbs2-GFP is cytoplasmic. Reason: GFP-tagged Pbs2 is cytoplasmic and excluded from the nucleus before and after osmotic stress; Pbs2 activates Hog1 in the cytoplasm, after which Hog1 enters the nucleus. Supporting Evidence: PMID:9755161 we found that HOG1, PBS2 and STE11 localize to the cytoplasm of unstressed cells. Following osmotic stress, HOG1, but neither PBS2 nor STE11, translocates into the nucleus.
GO:0005737 cytoplasm	IEA GO_REF:0000120	ACCEPT	Summary: IEA (ARBA / UniProt subcellular location) cytoplasm. Reason: GFP-tagged Pbs2 is cytoplasmic and excluded from the nucleus before and after osmotic stress; Pbs2 activates Hog1 in the cytoplasm, after which Hog1 enters the nucleus. Supporting Evidence: PMID:9755161 we found that HOG1, PBS2 and STE11 localize to the cytoplasm of unstressed cells. Following osmotic stress, HOG1, but neither PBS2 nor STE11, translocates into the nucleus.
GO:0005934 cellular bud tip	IDA PMID:10980703 Polarized localization of yeast Pbs2 depends on osmostress, ...	KEEP AS NON CORE	Summary: SGD IDA: kinase-dead Pbs2-GFP accumulates at bud tips during osmostress, dependent on Sho1 and Cdc42. Reason: The polarized pool at bud tips and bud necks (Sho1 sites) is transient during osmostress and was resolved with a catalytically inactive Pbs2 that traps the Sho1-bound intermediate. It marks the site where the Sho1 branch engages Pbs2, but it is not the steady-state location of the active kinase; retained as non-core. Supporting Evidence: PMID:10980703 Here we show that a catalytically inactive form of Pbs2 attains a highly polarised localization during osmostress. file:yeast/PBS2/PBS2-deep-research-falcon.md Recruitment depends on the Sho1 SH3 domain, the Pbs2 proline-rich interaction determinant around Pro96, and Cdc42.
GO:0005935 cellular bud neck	IDA PMID:10980703 Polarized localization of yeast Pbs2 depends on osmostress, ...	KEEP AS NON CORE	Summary: SGD IDA: kinase-dead Pbs2-GFP accumulates at the bud neck during osmostress. Reason: The polarized pool at bud tips and bud necks (Sho1 sites) is transient during osmostress and was resolved with a catalytically inactive Pbs2 that traps the Sho1-bound intermediate. It marks the site where the Sho1 branch engages Pbs2, but it is not the steady-state location of the active kinase; retained as non-core. Supporting Evidence: PMID:10980703 Here we show that a catalytically inactive form of Pbs2 attains a highly polarised localization during osmostress. file:yeast/PBS2/PBS2-deep-research-falcon.md Recruitment depends on the Sho1 SH3 domain, the Pbs2 proline-rich interaction determinant around Pro96, and Cdc42.
GO:0006468 protein phosphorylation	IDA PMID:7681220 An osmosensing signal transduction pathway in yeast.	ACCEPT	Summary: UniProt IDA: PBS2-dependent tyrosine phosphorylation of Hog1 in response to osmostress. Reason: Pbs2 phosphorylates Hog1 on Thr174/Tyr176; protein phosphorylation is a correct, general process term reflecting its catalytic activity. Supporting Evidence: PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity.
GO:0006606 protein import into nucleus	IMP PMID:15707964 Evidence that C-terminal non-kinase domain of Pbs2p has a ro...	MARK AS OVER ANNOTATED	Summary: SGD IMP: swapping the C-terminal region of D. hansenii Pbs2 for that of S. cerevisiae Pbs2 increases Hog1 nuclear translocation. Reason: Pbs2 does not perform nuclear import; it remains cytoplasmic. Hog1 phosphorylation (by Pbs2) is necessary and sufficient for Hog1 nuclear translocation, so the chimera effect most likely reflects the efficiency of Hog1 activation. The contribution is upstream of the import step and is captured by MAPKK activity in the p38MAPK cascade. Supporting Evidence: PMID:15707964 Here we show that by replacing C-terminal region of Dpbs2p with the homologous region of Pbs2p we could abrogate partial complementation exhibited by Dpbs2p and this was achieved due to increase in nuclear translocation of Hog1p. PMID:9755161 HOG1 phosphorylation is necessary and sufficient for nuclear translocation PMID:9755161 we found that HOG1, PBS2 and STE11 localize to the cytoplasm of unstressed cells. Following osmotic stress, HOG1, but neither PBS2 nor STE11, translocates into the nucleus.
GO:0006972 hyperosmotic response	IMP PMID:7681220 An osmosensing signal transduction pathway in yeast.	ACCEPT	Summary: SGD IMP: pbs2 mutants fail to restore osmotic balance after hyperosmotic shock. Reason: Pbs2 is required for osmoadaptation and directly participates as the MAPKK that activates Hog1. The cellular hyperosmotic response term (also annotated) is somewhat more precise. Supporting Evidence: PMID:7681220 Yeast genes were isolated that are required for restoring the osmotic gradient across the cell membrane in response to increased external osmolarity. PMID:7681220 Two of these genes, HOG1 and PBS2, encode members of the mitogen-activated protein kinase (MAP kinase) and MAP kinase kinase gene families, respectively.
GO:0007015 actin filament organization	IMP PMID:7941729 Positioning of cell growth and division after osmotic stress...	KEEP AS NON CORE	Summary: SGD IMP: pbs2 and hog1 mutants fail to repolarize actin to the original bud after osmotic stress. Reason: A downstream consequence of HOG signaling during recovery from osmostress, not an activity performed by Pbs2 on actin. Retained as non-core pathway output. Supporting Evidence: PMID:7941729 Mutants lacking the mitogen-activated protein (MAP) kinase encoded by HOG1 or the MAP kinase kinase encoded by PBS2 (previously HOG4) show a similar growth arrest after osmotic stress. PMID:7941729 Thus, the HOG pathway is required for repositioning of the actin cytoskeleton and the normal spatial patterns of cell growth after recovery from osmotic stress.
GO:0007231 osmosensory signaling pathway	IDA PMID:7681220 An osmosensing signal transduction pathway in yeast.	ACCEPT	Summary: UniProt IDA: PBS2-dependent Hog1 tyrosine phosphorylation defines an osmosensing signal transduction pathway. Reason: Pbs2 is the MAPKK at the convergence point of the Sln1 and Sho1 osmosensory branches and is required for osmostress-induced Hog1 phosphorylation. Core process. Supporting Evidence: PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity. PMID:7681220 These data define a signal transduction pathway that is activated by changes in the osmolarity of the extracellular environment.
GO:0007231 osmosensory signaling pathway	IMP PMID:7624781 Activation of yeast PBS2 MAPKK by MAPKKKs or by binding of a...	ACCEPT	Summary: SGD IMP: Pbs2 is activated by two independent osmosensor branches. Reason: Pbs2 is the MAPKK at the convergence point of the Sln1 and Sho1 osmosensory branches and is required for osmostress-induced Hog1 phosphorylation. Core process. Supporting Evidence: PMID:7624781 Pbs2p was activated by two independent signals that emanated from distinct cell-surface osmosensors. PMID:7624781 Pbs2p was activated by MAP kinase kinase kinases (MAPKKKs) Ssk2p and Ssk22p that are under the control of the SLN1-SSK1 two-component osmosensor. PMID:7624781 Alternatively, Pbs2p was activated by a mechanism that involves the binding of its amino terminal proline-rich motif to the Src homology 3 (SH3) domain of a putative transmembrane osmosensor Sho1p.
GO:0007232 osmosensory signaling pathway via Sho1 osmosensor	IPI PMID:15200958 Protein-protein interaction affinity plays a crucial role in...	ACCEPT	Summary: SGD IPI (with Sho1): Pbs2 binding to the Sho1 SH3 domain drives Sho1-branch HOG output. Reason: Pbs2 is recruited by the Sho1 SH3 domain and, via Ste11, activated in the Sho1 branch; binding affinity correlates with pathway output. Correct and core. Supporting Evidence: PMID:15200958 We demonstrate a strong linear correlation between the binding energy of these mutants and quantitative in vivo outputs from the HOG high-osmolarity response pathway controlled by Sho1p. PMID:7624781 Alternatively, Pbs2p was activated by a mechanism that involves the binding of its amino terminal proline-rich motif to the Src homology 3 (SH3) domain of a putative transmembrane osmosensor Sho1p. PMID:9180081 A second osmosensor, Sho1p, also activated Pbs2p and Hog1p, but did so through the Ste11p MAPKKK.
GO:0010494 cytoplasmic stress granule	HDA PMID:26777405 ATPase-Modulated Stress Granules Contain a Diverse Proteome ...	KEEP AS NON CORE	Summary: High-throughput proteomics of yeast stress granule cores reporting Pbs2. Reason: Single high-throughput dataset; the protein list is in supplementary data not in the cache and there is no targeted follow-up on Pbs2 in stress granules. Not contradicted, but not part of Pbs2's known function; retained as non-core. Supporting Evidence: PMID:26777405 Proteomic analysis of stress granule cores reveals a dense network of protein-protein interactions
GO:0016239 positive regulation of macroautophagy	IMP PMID:40524543 Pbs2 regulates late-stage macroautophagy in Saccharomyces ce...	KEEP AS NON CORE	Summary: SGD IMP: pbs2 deletion reduces nitrogen-starvation macroautophagy at a late stage, independently of Hog1. Reason: The phenotype is Hog1-independent and acts after autophagosome closure, but the mechanism (substrate, kinase dependence) is unknown. The acts_upstream_of_or_within assignment is appropriate; not a core function. Supporting Evidence: PMID:40524543 Furthermore, the influence of Pbs2 on macroautophagy was shown to be independent of Hog1, a well-known downstream factor of Pbs2. PMID:40524543 In conclusion, Pbs2 regulates the late stages of macroautophagy induced by nitrogen starvation.
GO:0031416 NatB complex	IDA PMID:12783868 Nat3p and Mdm20p are required for function of yeast NatB Nal...	UNDECIDED	Summary: UniProt IDA placing Pbs2 in the NatB N-terminal acetyltransferase complex. Reason: Kept as UNDECIDED rather than REMOVE because the cached paper is abstract-only, so this experimental row cannot be checked against the full text; the evidence below strongly suggests a NAT3 mis-attribution. The cited abstract states that NatB consists of Nat3p and Mdm20p. Pbs2 has no role or domain related to N-acetylation, UniProt's own P08018 entry does not list NatB, and SGD (which annotates NAT3 to NatB from this paper) carries no such annotation for PBS2. Almost certainly an accession error in the UniProt-assigned row. Supporting Evidence: PMID:12783868 NatB is composed of the interacting Nat3p and Mdm20p subunits, both of which are required for acetyltransferase activity. file:yeast/PBS2/PBS2-uniprot.txt Interacts with NBP2, PTC1, SHO1 and STE11.
GO:0032991 protein-containing complex	IEA GO_REF:0000117	KEEP AS NON CORE	Summary: ARBA IEA for protein-containing complex. Reason: Pbs2 does form complexes with Sho1, Ste11, Hog1 and Nbp2-Ptc1, so the term is not wrong, but it is uninformative; the scaffold role is captured by MAP kinase scaffold activity. Supporting Evidence: PMID:9180081 The MAPKK Pbs2p bound to the Sho1p osmosensor, the MAPKKK Ste11p, and the MAPK Hog1p. Thus, Pbs2p may serve as a scaffold protein. PMID:14685261 In this work, we show that the SH3 domain-containing protein Nbp2 negatively regulates Hog1 by recruiting Ptc1 to the Pbs2-Hog1 complex.
GO:0038066 p38MAPK cascade	IEA GO_REF:0000117	ACCEPT	Summary: ARBA IEA for p38MAPK cascade. Reason: The HOG pathway is the yeast p38-type (stress-activated) MAPK cascade; Pbs2 is its MAPKK and phosphorylates Hog1. Core process. Supporting Evidence: PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity. PMID:7624781 Pbs2p was activated by MAP kinase kinase kinases (MAPKKKs) Ssk2p and Ssk22p that are under the control of the SLN1-SSK1 two-component osmosensor.
GO:0038066 p38MAPK cascade	IGI PMID:7624781 Activation of yeast PBS2 MAPKK by MAPKKKs or by binding of a...	ACCEPT	Summary: SGD IGI with SSK22: Pbs2 acts downstream of the Ssk2/Ssk22 MAPKKKs. Reason: The HOG pathway is the yeast p38-type (stress-activated) MAPK cascade; Pbs2 is its MAPKK and phosphorylates Hog1. Core process. Supporting Evidence: PMID:7624781 Pbs2p was activated by MAP kinase kinase kinases (MAPKKKs) Ssk2p and Ssk22p that are under the control of the SLN1-SSK1 two-component osmosensor.
GO:0038066 p38MAPK cascade	IGI PMID:7624781 Activation of yeast PBS2 MAPKK by MAPKKKs or by binding of a...	ACCEPT	Summary: SGD IGI with SSK2: Pbs2 acts downstream of the Ssk2/Ssk22 MAPKKKs. Reason: The HOG pathway is the yeast p38-type (stress-activated) MAPK cascade; Pbs2 is its MAPKK and phosphorylates Hog1. Core process. Supporting Evidence: PMID:7624781 Pbs2p was activated by MAP kinase kinase kinases (MAPKKKs) Ssk2p and Ssk22p that are under the control of the SLN1-SSK1 two-component osmosensor.
GO:0038066 p38MAPK cascade	IMP PMID:15707964 Evidence that C-terminal non-kinase domain of Pbs2p has a ro...	ACCEPT	Summary: SGD IMP: the Pbs2 C-terminal region affects Hog1 activation/nuclear accumulation. Reason: The HOG pathway is the yeast p38-type (stress-activated) MAPK cascade; Pbs2 is its MAPKK and phosphorylates Hog1. Core process. Supporting Evidence: PMID:15707964 Here we show that by replacing C-terminal region of Dpbs2p with the homologous region of Pbs2p we could abrogate partial complementation exhibited by Dpbs2p and this was achieved due to increase in nuclear translocation of Hog1p. PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity.
GO:0071470 cellular response to osmotic stress	IEA GO_REF:0000117	ACCEPT	Summary: ARBA IEA for cellular response to osmotic stress. Reason: Correct, somewhat general parent of cellular hyperosmotic response. Supporting Evidence: PMID:7681220 Yeast genes were isolated that are required for restoring the osmotic gradient across the cell membrane in response to increased external osmolarity.
GO:0071474 cellular hyperosmotic response	IBA GO_REF:0000033	ACCEPT	Summary: PAINT IBA for cellular hyperosmotic response. Reason: Pbs2 is required for the cellular response to hyperosmotic stress as the MAPKK that relays Sln1- and Sho1-branch signals to Hog1. Core process. Supporting Evidence: PMID:7681220 Yeast genes were isolated that are required for restoring the osmotic gradient across the cell membrane in response to increased external osmolarity. PMID:7624781 Pbs2p was activated by two independent signals that emanated from distinct cell-surface osmosensors.
GO:0071474 cellular hyperosmotic response	IGI PMID:7624781 Activation of yeast PBS2 MAPKK by MAPKKKs or by binding of a...	ACCEPT	Summary: SGD IGI with SSK22 for cellular hyperosmotic response. Reason: Pbs2 is required for the cellular response to hyperosmotic stress as the MAPKK that relays Sln1- and Sho1-branch signals to Hog1. Core process. Supporting Evidence: PMID:7624781 Pbs2p was activated by MAP kinase kinase kinases (MAPKKKs) Ssk2p and Ssk22p that are under the control of the SLN1-SSK1 two-component osmosensor.
GO:0071474 cellular hyperosmotic response	IGI PMID:7624781 Activation of yeast PBS2 MAPKK by MAPKKKs or by binding of a...	ACCEPT	Summary: SGD IGI with SSK2 for cellular hyperosmotic response. Reason: Pbs2 is required for the cellular response to hyperosmotic stress as the MAPKK that relays Sln1- and Sho1-branch signals to Hog1. Core process. Supporting Evidence: PMID:7624781 Pbs2p was activated by MAP kinase kinase kinases (MAPKKKs) Ssk2p and Ssk22p that are under the control of the SLN1-SSK1 two-component osmosensor.
GO:0106310 protein serine kinase activity	IEA GO_REF:0000116	MARK AS OVER ANNOTATED	Summary: Rhea-based IEA for protein serine kinase activity (RHEA:17989, via EC 2.7.12.2). Reason: The EC 2.7.12.2 class includes a generic serine reaction, but Pbs2's characterized physiological reaction is threonine/tyrosine dual phosphorylation of Hog1 (Thr174/Tyr176); UniProt tags only the Thr and Tyr reactions with experimental evidence. Serine phosphorylation by Pbs2 is not established; the function is best captured by MAP kinase kinase activity. Supporting Evidence: PMID:7681220 A rapid, PBS2-dependent tyrosine phosphorylation of HOG1 protein occurred in response to increases in extracellular osmolarity. PMID:38270553 The activity of Hog1p was specifically enhanced at these proline-adjacent sites on Dot1p upon Hog1p activation by the osmostress-responsive MAP kinase kinase PBS2 (Pbs2p).

Gene Description

Existing Annotations Review

Core Functions

MAP kinase kinase of the HOG osmostress pathway: activated by Ssk2/Ssk22 (Sln1 branch) or Ste11 (Sho1 branch), Pbs2 dually phosphorylates Hog1 on Thr174/Tyr176 in the cytoplasm, relaying osmosensory signals to the p38-type MAPK.

Scaffold of the Sho1 branch: Pbs2 binds the Sho1 SH3 domain through its N-terminal proline-rich motif and also binds Ste11 and Hog1, acting with Sho1 as a co-scaffold that directs Ste11 to Pbs2 and insulates HOG signaling from other Ste11-dependent MAPK pathways.

References

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SGD

SGD gene description for PBS2 (yeast)

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