UniProt P10080 (locus YHL034C; canonical gene symbol SBP1) is the RGG/RRM RNA-binding protein Sbp1. SSB1 and SSBR1 are historical synonyms for this protein and must not be confused with the unrelated ribosome-associated Hsp70 chaperone Ssb1/Ssb2. Sbp1 is built from two RRM domains separated by a low-complexity RGG (Arg-Gly-Gly) box. Its core molecular function is broadly sequence-non-specific mRNA binding with a positional preference for the 5' UTR, while the PAB1 transcript contains a specifically recognized A-rich 5'-UTR tract. Sbp1 acts as a translation repressor through RGG-dependent RNA binding and assembly with Pab1/eIF4G-containing initiation complexes, although whether Sbp1 binds eIF4G directly or through RNA/Pab1 is disputed. It thereby promotes transition of mRNAs out of active translation. Sbp1 is predominantly cytoplasmic in log phase and relocalizes to P-bodies and stress granules under stress; it is a P-body disassembly factor during recovery from stress, dissolving Edc3/Dhh1/Scd6 foci in an RGG- and arginine-methylation-dependent manner. The older literature additionally reports a nucleolar, snR10/snR11-associated form, but the well-characterized contemporary function is cytoplasmic mRNP/translation control.
Definition: The disassembly of a cytoplasmic processing body (P-body), an mRNP granule containing translationally repressed mRNAs and mRNA-decay factors.
Justification: The cited experiment is specifically about P-body disassembly, but GO currently provides cytoplasmic stress granule disassembly (GO:0035617) and P granule disassembly (GO:1903864), not a term for P-body disassembly. GO:0032984 protein-containing complex disassembly is the best available interim parent but loses the biologically important granule identity.
Supporting Evidence:
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003729 mRNA binding | IBA GO_REF:0000033 | ACCEPT | Summary: mRNA binding is a core molecular function of Sbp1. CLIP analysis identified Sbp1 among P-body/stress-granule-associated RNA-binding proteins and showed it binds mRNAs with positional rather than strong sequence specificity, with a clear preference for the 5' UTR. The binding is mediated by its two RRM domains plus the RGG box. Reason: Core molecular function; well supported by phylogenetic inference and by direct CLIP evidence in S. cerevisiae. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN002345455 Β· PANTHER:PTN002345455 SUPPORTS TRANSFER PTHR23003 PAINT places mRNA binding on PTN002345455, the RRM/RGG clade that contains S. cerevisiae Sbp1; the node is consistent with the target's direct CLIP evidence for mRNA binding. Supporting Evidence: file:yeast/SBP1/SBP1-deep-research-falcon.md A global yeast mRNP study using CLIP identified Sbp1 among a set of PB/SG-associated RBPs (with Pat1, Lsm1, Dhh1) and found that Sbp1 exhibits **positional specificity** on transcripts: Sbp1 binding shows a clear preference for the **5β² UTR**, rather than strong sequence specificity |
| GO:0005634 nucleus | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Nuclear localization is phylogenetically inferred and is consistent only with the older nucleolar-form characterization of SSB1 (snR10/snR11-associated). The well-characterized contemporary function of Sbp1 is cytoplasmic; the falcon deep research synthesis does not address the historical nuclear site of action. Reason: Supported by historical immunofluorescence and phylogenetic inference, but retained as non-core because the well-characterized contemporary function is cytoplasmic. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: PANTHER:PTN002345455 Β· PANTHER:PTN002345455 SUPPORTS TRANSFER The same PTHR23003 PAINT node carries nuclear localization for Sbp1's conserved RRM/RGG clade; this is defensible for Sbp1 but secondary to its cytoplasmic mRNP role in contemporary experiments. Supporting Evidence: PMID:2823109 examination of the subcellular distribution of SSB1 by immunofluorescence microscopy indicated that SSB1 is a nuclear protein, predominantly located in the nucleolus. |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: Cytoplasm is the constitutive subcellular location of Sbp1, consistent with its cytoplasmic mRNP/translation-control function and phylogenetic inference. Reason: Core, constitutive localization; consistent across phylogenetic inference and direct experimental evidence. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN002345455 Β· PANTHER:PTN002345455 SUPPORTS TRANSFER PTHR23003 PAINT places cytoplasmic localization on the same Sbp1/Npl3 RRM/RGG node, matching Sbp1's direct cytoplasmic localization and cytoplasmic translation-control role. Supporting Evidence: file:yeast/SBP1/SBP1-deep-research-falcon.md Sbp1 itself is largely cytoplasmic in mid-log phase and accumulates in PBs under stress conditions (e.g., glucose deprivation/high cell density) or upon overexpression, consistent with conditional relocalization during mRNP remodeling |
| GO:1990904 ribonucleoprotein complex | IBA GO_REF:0000033 | ACCEPT | Summary: Sbp1 is a component of cytoplasmic messenger ribonucleoprotein (mRNP) complexes, consistent with its role in regulating mRNP state transitions between translation and translationally repressed/decay-competent states (P-bodies and stress granules). Reason: Supported by mRNP/CLIP studies placing Sbp1 within cytoplasmic mRNP complexes. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: PANTHER:PTN000543776 Β· PANTHER:PTN000543776 SUPPORTS TRANSFER PTHR23003 PAINT places ribonucleoprotein-complex membership on PTN000543776, a eukaryotic RRM node currently seeded by FB:FBgn0267790 and the SGD MRD1 identifier S000006316. MRD1 is absent from the local PTHR23003 member table, but this broad complex-membership transfer is compatible with direct yeast evidence that Sbp1 acts in cytoplasmic mRNPs. Supporting Evidence: file:yeast/SBP1/SBP1-deep-research-falcon.md SBP1 encodes an RGG/RRM RNA-binding protein that regulates cytoplasmic mRNP state transitions. |
| GO:0000932 P-body | IEA GO_REF:0000044 | ACCEPT | Summary: Sbp1 accumulates in P-bodies under stress and upon overexpression, and is itself a P-body disassembly factor during recovery from stress. P-body localization is a genuine and functionally meaningful aspect of Sbp1 biology, though it is stress/condition-dependent rather than constitutive. Reason: Genuine, condition-dependent localization that is the site of Sbp1's core P-body disassembly function during stress recovery. Supporting Evidence: file:yeast/SBP1/SBP1-deep-research-falcon.md Sbp1 itself is largely cytoplasmic in mid-log phase and accumulates in PBs under stress conditions (e.g., glucose deprivation/high cell density) or upon overexpression, consistent with conditional relocalization during mRNP remodeling |
| GO:0003676 nucleic acid binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Generic nucleic-acid binding inferred from InterPro RRM-domain signatures. The activity is correct but the more specific child terms RNA binding (GO:0003723) and especially mRNA binding (GO:0003729) / mRNA 5'-UTR binding (GO:0048027) better capture the demonstrated function. Reason: Correct but uninformatively general; superseded by more specific RNA/mRNA binding annotations. Supporting Evidence: file:yeast/SBP1/SBP1-deep-research-falcon.md describes the characteristic architecture of **two RRMs separated by an RGG box** |
| GO:0003723 RNA binding | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: RNA binding is well supported by Sbp1's two-RRM-plus-RGG architecture and by direct CLIP evidence. The more specific child term mRNA binding (GO:0003729) better captures the experimentally demonstrated activity, but this parent term is also correct. Reason: Correct but non-core; the more specific mRNA binding term is preferred where supported, but RNA binding is accurate. Supporting Evidence: file:yeast/SBP1/SBP1-deep-research-falcon.md The literature synthesized here explicitly studies *Saccharomyces cerevisiae* Sbp1/Sbp1p (also referred to historically as Ssb1p) and describes the characteristic architecture of **two RRMs separated by an RGG box** |
| GO:0005730 nucleolus | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Nucleolar localization (UniProt subcellular-location mapping) reflects the older SSB-1 characterization as a nucleolar snR10/snR11-associated protein. Distinct from the contemporary cytoplasmic mRNP/translation-control function; falcon synthesis does not address nucleolar localization. Reason: Historical nucleolar evidence separate from the well-characterized cytoplasmic function; retained as non-core. Supporting Evidence: PMID:2823109 examination of the subcellular distribution of SSB1 by immunofluorescence microscopy indicated that SSB1 is a nuclear protein, predominantly located in the nucleolus. |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: Cytoplasm is the constitutive subcellular location of Sbp1, where it carries out its translation-repression function (UniProt subcellular-location mapping). Reason: Core, constitutive localization; well supported by experimental evidence. Supporting Evidence: file:yeast/SBP1/SBP1-deep-research-falcon.md Sbp1 itself is largely cytoplasmic in mid-log phase and accumulates in PBs under stress conditions (e.g., glucose deprivation/high cell density) or upon overexpression, consistent with conditional relocalization during mRNP remodeling |
| GO:0010494 cytoplasmic stress granule | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Sbp1 localizes to both P-bodies and cytoplasmic stress granules under stress. This is a genuine but stress-conditional localization. Reason: Genuine but condition-dependent localization rather than a constitutive site of action. Supporting Evidence: PMID:23222640 Sbp1 can be contrasted to the others since it is found in both P-bodies and stress granules |
| GO:0005515 protein binding | IPI PMID:16429126 Proteome survey reveals modularity of the yeast cell machine... | REMOVE | Summary: Generic protein binding from a high-throughput interactome survey. The biologically meaningful protein-protein interactions of Sbp1 are captured by the specific protein-sequestering interaction with the P-body component Edc3 (GO:0140311), underlying P-body disassembly. Reason: Protein binding is uninformative; GO:0140311 captures the experimentally established competitive Edc3 interaction and its mechanistic meaning. |
| GO:0005515 protein binding | IPI PMID:16554755 Global landscape of protein complexes in the yeast Saccharom... | REMOVE | Summary: Generic protein binding from a high-throughput protein-complex survey. More specific protein sequestering activity toward the P-body component Edc3 (GO:0140311) captures a functionally relevant interaction. Reason: Protein binding is uninformative; GO:0140311 captures the experimentally established competitive Edc3 interaction and its mechanistic meaning. |
| GO:0005515 protein binding | IPI PMID:37968396 The social and structural architecture of the yeast protein ... | REMOVE | Summary: Generic protein binding from a yeast interactome study. The functionally relevant, directly established interaction is competitive binding to the P-body component Edc3 (GO:0140311), underlying P-body disassembly. Reason: Protein binding is uninformative; GO:0140311 captures the experimentally established competitive Edc3 interaction and its mechanistic meaning. |
| GO:0045947 negative regulation of translational initiation | IDA PMID:28986506 Sbp1 modulates the translation of Pab1 mRNA in a poly(A)- an... | ACCEPT | Summary: Negative regulation of translation initiation is a CORE function of Sbp1. It binds the A-rich PAB1 5' UTR and uses its RGG region to assemble an RNA-dependent repressed mRNP. Increasing Sbp1 inhibits both cap-dependent and cap-independent initiation of Pab1 mRNA. Reason: Direct experimental evidence establishes this as a core biological role of Sbp1; falcon synthesis elevates it from peripheral to core (revised from KEEP_AS_NON_CORE). Supporting Evidence: PMID:28986506 a decreased translation activity in the presence of an increasing amount of Sbp1 indicated an inhibitory function of this protein in both cap-dependent and cap-independent initiation of the Pab1 mRNA |
| GO:0045947 negative regulation of translational initiation | IMP PMID:28986506 Sbp1 modulates the translation of Pab1 mRNA in a poly(A)- an... | ACCEPT | Summary: Negative regulation of translation initiation is a CORE function of Sbp1, supported here by mutational/phenotypic (IMP) evidence (e.g. RGG- and poly(A)-dependent modulation of Pab1 mRNA translation). The full-text study supports an RNA-dependent Sbp1-Pab1-eIF4G complex rather than direct Sbp1-eIF4G binding. Reason: Core biological role supported by direct mutant phenotype evidence; revised from KEEP_AS_NON_CORE based on falcon synthesis. Supporting Evidence: PMID:28986506 Substitution of the RGG repeats with GS repeats, or methylation of arginines in the RGG repeats, abolishes the inhibitory function of Sbp1 on the Pab1 mRNA in both cap-dependent and cap-independent initiation pathways |
| GO:0045947 negative regulation of translational initiation | IDA PMID:39617253 An Intrinsically Disordered RNA Binding Protein Modulates mR... | ACCEPT | Summary: Negative regulation of translation initiation is a CORE function of Sbp1. As an intrinsically disordered RGG/RRM RNA-binding protein it modulates mRNA translation and storage, repressing initiation through 5'-UTR engagement. Reason: Core biological role; revised from KEEP_AS_NON_CORE based on falcon synthesis and direct evidence. Supporting Evidence: PMID:39617253 the binding of Sbp1 to the 5'UTRs of mRNAs represses both cap-dependent and cap-independent translation initiation of proteins |
| GO:0045947 negative regulation of translational initiation | IMP PMID:39617253 An Intrinsically Disordered RNA Binding Protein Modulates mR... | ACCEPT | Summary: Negative regulation of translation initiation is a CORE function of Sbp1, supported by mutant phenotype (IMP) evidence. Its 5'-UTR binding and RGG region are central to repression of both cap-dependent and cap-independent initiation. Reason: Core biological role supported by mutant phenotypes; revised from KEEP_AS_NON_CORE based on falcon synthesis. Supporting Evidence: PMID:39617253 the binding of Sbp1 to the 5'UTRs of mRNAs represses both cap-dependent and cap-independent translation initiation of proteins |
| GO:0048027 mRNA 5'-UTR binding | IDA PMID:28986506 Sbp1 modulates the translation of Pab1 mRNA in a poly(A)- an... | ACCEPT | Summary: A precise, core molecular function: Sbp1's two distal RRMs bind specifically and cooperatively to the poly(A)-rich sequence in the PAB1 mRNA 5' UTR. This RNA interaction is required for repression of cap-dependent and cap-independent initiation of Pab1 mRNA. Reason: Specific, experimentally supported molecular function central to Sbp1's role in translation control. Supporting Evidence: PMID:28986506 the two distal RRMs of Sbp1 bind to the poly(A) sequence in the 5'UTR of the Pab1 mRNA specifically and cooperatively |
| GO:0048027 mRNA 5'-UTR binding | IDA PMID:39617253 An Intrinsically Disordered RNA Binding Protein Modulates mR... | ACCEPT | Summary: Core molecular function: Sbp1 preferentially binds the 5' UTR of target mRNAs. The cited study links this 5'-UTR binding directly to repression of both cap-dependent and cap-independent translation initiation. Reason: Specific, experimentally supported molecular function central to Sbp1's role in translation control. Supporting Evidence: PMID:39617253 the binding of Sbp1 to the 5'UTRs of mRNAs represses both cap-dependent and cap-independent translation initiation of proteins |
| GO:0035617 cytoplasmic stress granule disassembly | IDA PMID:35440550 Low complexity RGG-motif sequence is required for Processing... | MODIFY | Summary: Sbp1 is a granule disassembly factor during recovery from stress. Roy et al. 2022 (PMID:35440550) is explicitly about PROCESSING BODY (P-body) disassembly: the title is "Low complexity RGG-motif sequence is required for Processing body (P-body) disassembly," and all three markers tested (Edc3, Dhh1, Scd6) are P-body components. After sodium-azide stress and recovery, delta-sbp1 cells are defective in disassembly of these P-body foci, and purified Sbp1 dissolves Edc3 assemblies in vitro in an RGG- and arginine-methylation-dependent manner. The annotated term GO:0035617 is cytoplasmic stress granule disassembly, a distinct GO process; the evidence supports P-body disassembly. There is no specific "P-body disassembly" / "processing body disassembly" term in GO (verified via OLS), so the closest accurate available term is GO:0032984 (protein-containing complex disassembly), which captures the demonstrated disaggregation of the P-body Edc3 protein assembly. Reason: The cited evidence (Roy et al. 2022, PMID:35440550) demonstrates P-body disassembly, not cytoplasmic stress granule disassembly; GO:0035617 is the wrong process. No specific P-body/processing-body disassembly term exists in GO (confirmed via OLS - searches for "P-body disassembly" and "processing body disassembly" return no GO class), so the most accurate available replacement is GO:0032984 (protein-containing complex disassembly), matching the observed dissolution of Edc3 P-body assemblies. Proposed replacements: protein-containing complex disassembly Supporting Evidence: PMID:35440550 we identify RGG-motif containing translation repressor protein Sbp1 as a disassembly factor of P-bodies since disassembly of P-bodies is defective in Ξsbp1 |
| GO:0000932 P-body | IDA PMID:23222640 Global analysis of yeast mRNPs. | ACCEPT | Summary: Direct evidence places Sbp1 among P-body/stress-granule-associated RNA-binding proteins. P-body engagement is a genuine, functionally central but stress/condition-dependent aspect of Sbp1 biology (it both localizes to and promotes disassembly of P-bodies). Reason: Genuine condition-dependent localization that is the site of Sbp1's core P-body disassembly function. Supporting Evidence: PMID:23222640 Sbp1 can be contrasted to the others since it is found in both P-bodies and stress granules |
| GO:0010494 cytoplasmic stress granule | IDA PMID:23222640 Global analysis of yeast mRNPs. | KEEP AS NON CORE | Summary: Sbp1 is found in cytoplasmic stress granules as well as P-bodies under stress. This is a genuine but stress-conditional localization. Reason: Genuine but condition-dependent localization rather than a constitutive site of action. Supporting Evidence: PMID:23222640 Sbp1 can be contrasted to the others since it is found in both P-bodies and stress granules |
| GO:0010494 cytoplasmic stress granule | HDA PMID:26777405 ATPase-Modulated Stress Granules Contain a Diverse Proteome ... | KEEP AS NON CORE | Summary: High-throughput proteomic identification of Sbp1 in stress granules, consistent with the focused microscopy showing stress-dependent Sbp1 stress-granule localization. Genuine but condition-dependent. Reason: Genuine but condition-dependent localization; consistent with focused studies. Sbp1 is identified in the study's supplementary stress-granule core proteome; the cached article body describes the proteomic assay but does not name individual supplementary-table hits. Supporting Evidence: PMID:26777405 Proteomic analysis of stress granule cores reveals a dense network of protein-protein interactions and links between stress granules and human diseases and identifies ATP-dependent helicases and protein remodelers as conserved stress granule components. |
| GO:0003729 mRNA binding | HDA PMID:23222640 Global analysis of yeast mRNPs. | ACCEPT | Summary: mRNA binding is a core molecular function, directly demonstrated by CLIP in the Mitchell et al. global mRNP analysis, which mapped Sbp1's transcriptome-wide binding with a 5'-UTR positional preference. Reason: Core molecular function with direct transcriptome-wide binding evidence. Supporting Evidence: PMID:23222640 In contrast to Lsm1 and Pat1, Sbp1 shows bias towards the 5β² UTR |
| GO:0003729 mRNA binding | IDA PMID:23222640 Global analysis of yeast mRNPs. | ACCEPT | Summary: mRNA binding is a core molecular function. Direct CLIP evidence shows Sbp1 binds mRNAs with positional (5'-UTR) rather than strong sequence specificity, mediated by its two RRMs and RGG box. Reason: Core molecular function with direct experimental support. Supporting Evidence: PMID:23222640 In contrast to Lsm1 and Pat1, Sbp1 shows bias towards the 5β² UTR |
| GO:0000932 P-body | IDA PMID:16782896 Sbp1p affects translational repression and decapping in Sacc... | ACCEPT | Summary: Foundational evidence (Segal et al. 2006) places Sbp1 in P-body biology: overexpression increases P-body size and number, whereas loss of Sbp1 reduces P-body formation. The curator's localization annotation is retained; the cached abstract does not include the microscopy details from the full paper. Reason: Genuine condition-dependent localization established in the foundational Segal 2006 study and central to Sbp1's P-body remodeling function. Supporting Evidence: PMID:16782896 Sbp1p overexpression restores normal decay rates in decapping-defective strains and increases P-body size and number. |
| GO:0005730 nucleolus | IDA PMID:2121740 SSB-1 of the yeast Saccharomyces cerevisiae is a nucleolar-s... | KEEP AS NON CORE | Summary: Nucleolar localization derives from the older characterization of "SSB-1" as a nucleolar-specific, silver-binding protein associated with the snR10 and snR11 small nuclear RNAs. This is a distinct, historical strand of evidence that the contemporary cytoplasmic mRNP/translation-control literature (and the falcon deep research synthesis) does not address. Retained as non-core pending reconciliation of the nucleolar and cytoplasmic bodies of evidence. Reason: Genuine IDA evidence from the original snRNA-association studies, but not part of the well-characterized contemporary cytoplasmic function; falcon synthesis does not address nucleolar localization. Supporting Evidence: PMID:2121740 SSB-1 colocalized with fibrillarin in a double-label immunofluorescence mapping experiment to the yeast nucleolus. |
| GO:0005730 nucleolus | IDA PMID:2823109 Saccharomyces cerevisiae SSB1 protein and its relationship t... | KEEP AS NON CORE | Summary: Nucleolar localization from the original SSB1 characterization relating it to nucleolar RNA-binding proteins. Same caveat as the snR10/snR11 study: this historical nucleolar evidence is separate from the contemporary cytoplasmic mRNP/translation-control function and is not addressed by the falcon synthesis. Reason: Genuine historical IDA evidence, but not part of the well-characterized contemporary cytoplasmic function. Supporting Evidence: PMID:2823109 examination of the subcellular distribution of SSB1 by immunofluorescence microscopy indicated that SSB1 is a nuclear protein, predominantly located in the nucleolus. |
| GO:0005737 cytoplasm | IDA PMID:16782896 Sbp1p affects translational repression and decapping in Sacc... | ACCEPT | Summary: Cytoplasm is the constitutive site of action for Sbp1. It is largely cytoplasmic in mid-log phase, where it carries out translational repression, relocalizing to P-bodies/stress granules only under stress. Reason: Core, constitutive subcellular localization where Sbp1 performs its translation-control function. Supporting Evidence: file:yeast/SBP1/SBP1-deep-research-falcon.md Sbp1 itself is largely cytoplasmic in mid-log phase and accumulates in PBs under stress conditions (e.g., glucose deprivation/high cell density) or upon overexpression, consistent with conditional relocalization during mRNP remodeling |
| GO:0017148 negative regulation of translation | IDA PMID:22284680 Scd6 targets eIF4G to repress translation: RGG motif protein... | ACCEPT | Summary: Negative regulation of translation is a CORE function. Rajyaguru et al. showed Sbp1 represses translation in an RGG-motif-dependent manner and reported an Sbp1-eIF4G interaction. A later purified-protein study found that this interaction is not direct and is instead mediated by RNA or a ternary protein. The more specific child term negative regulation of translational initiation (GO:0045947) is also annotated and preferred. Reason: Core biological role with biochemical evidence for repression; the directness of the reported Sbp1-eIF4G interaction is disputed by later purified-protein work. Supporting Evidence: PMID:22284680 Npl3 and Sbp1, also directly bind eIF4G and repress translation in a manner dependent on their RGG motifs PMID:28986506 Using purified RNA-free proteins, we observed no direct interactions between eIF4G1 and Sbp1, and between eIF4G1 and the RGG domain of Sbp1 (Sbp1RGG) PMID:42371698 Loss of Sbp1 leads to selective translational upregulation of key autophagy genes ATG1, ATG2, and ATG9. |
| GO:0031370 eukaryotic initiation factor 4G binding | IDA PMID:22284680 Scd6 targets eIF4G to repress translation: RGG motif protein... | ACCEPT | Summary: Rajyaguru et al. reported RGG-dependent Sbp1-eIF4G binding by GST pulldown. Later experiments with purified RNA-free proteins detected no direct interaction and concluded that the earlier association was likely mediated by endogenous RNA or a ternary protein. The curator's IDA annotation is retained, but direct binding is explicitly disputed. Reason: Retain the curator's specific interaction annotation because the original study reported RGG-dependent binding, while recording the later contradictory purified-protein result rather than presenting direct binding as settled. Supporting Evidence: PMID:22284680 Npl3 and Sbp1, also directly bind eIF4G and repress translation in a manner dependent on their RGG motifs PMID:28986506 Using purified RNA-free proteins, we observed no direct interactions between eIF4G1 and Sbp1, and between eIF4G1 and the RGG domain of Sbp1 (Sbp1RGG) |
| GO:0140311 protein sequestering activity | IDA PMID:35440550 Low complexity RGG-motif sequence is required for Processing... | NEW | Summary: NEW annotation capturing the molecular basis of Sbp1's P-body disassembly activity. Roy et al. 2022 (PMID:35440550) showed by binding studies with purified proteins that Sbp1 physically interacts with Edc3 and that the Sbp1-Edc3 interaction COMPETES with Edc3-Edc3 self-association; addition of purified Sbp1 (but not the RGG-deletion mutant) significantly decreases Edc3 assemblies. By binding Edc3 to prevent it from interacting with its self-assembly partners, Sbp1 exhibits protein sequestering activity, which is mechanistically distinct from its mRNA-binding/translation-repression functions. This term supersedes the generic protein binding (GO:0005515) annotations for the Edc3 interaction. Reason: Specific, informative MF whose definition covers binding a protein to prevent its interaction with other partners. That matches the observed competition between Sbp1-Edc3 and Edc3-Edc3 binding and captures the RNA-independent disruption activity underlying P-body disassembly. The separate GO:0032984 replacement and proposed P-body-disassembly term capture the dissolution of existing assemblies that this MF does not fully express; GO:0140311 replaces uninformative protein binding for the competitive interaction itself. Supporting Evidence: PMID:35440550 Binding studies using purified proteins revealed that Sbp1 physically interacts with Edc3 and Sbp1-Edc3 interaction competes with Edc3-Edc3 interaction |
| GO:0032055 negative regulation of translation in response to stress | IMP PMID:16782896 Sbp1p affects translational repression and decapping in Sacc... | KEEP AS NON CORE | Summary: Sbp1 represses translation and promotes P-body engagement particularly under stress conditions (e.g. glucose deprivation), consistent with a stress-responsive translational-repression role. This is a more contextualized child of the core negative-regulation-of-translation function. Reason: Valid stress-contextualized refinement of the core translational-repression role; kept as non-core relative to the general repression function. Supporting Evidence: PMID:16782896 Sbp1p promotes translational repression of mRNA during glucose deprivation |
| GO:0003723 RNA binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: The InterPro RRM-domain mapping correctly captures Sbp1's RNA-binding capacity. It is less specific than the direct mRNA-binding and mRNA 5'-UTR-binding annotations but is consistent with Sbp1's two RRM domains and its demonstrated mRNA binding. Reason: RNA binding is accurate for Sbp1 but non-core; the more specific mRNA binding and mRNA 5'-UTR binding rows better describe the characterized activity, but the conserved RRM signature and direct CLIP/PAB1 5'-UTR assays support the broader parent term as well. Supporting Evidence: PMID:28986506 the two distal RRMs of Sbp1 bind to the poly(A) sequence in the 5'UTR of the Pab1 mRNA specifically and cooperatively |
| GO:0005737 cytoplasm | EXP PMID:23222640 Global analysis of yeast mRNPs. | ACCEPT | Summary: Mitchell et al. directly placed Sbp1 in cytoplasmic mRNP granules under glucose-deprivation stress, consistent with its cytoplasmic translation-repression and P-body/stress-granule roles. Reason: Cytoplasm is a core location for Sbp1's mRNA-binding and translation-control program. This direct UniProt EXP row from PMID:23222640 is consistent with the accepted cytoplasm IBA, UniProt SubCell, and focused yeast localization rows. Supporting Evidence: PMID:23222640 Sbp1 can be contrasted to the others since it is found in both P-bodies and stress granules |
| GO:0006364 rRNA processing | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: PTHR23003 now places an rRNA-processing assertion on PTN000543777, seeded by SGD:S000006316/MRD1 and zebrafish evidence. Sbp1 has older nucleolar snR10/snR11 association evidence, but the SBP1 literature does not directly show that it executes a step in rRNA processing. Reason: This is an over-broad process transfer from an RRM-family PAINT node into the functionally divergent SBP1/SF56 branch. PMID:2121740 observed SSB-1/Sbp1 in a nucleolar snRNP with snR10 and inferred possible rRNA-processing involvement because snR10 participates in pre-rRNA processing, but that indirect association is insufficient to establish that Sbp1 itself performs rRNA processing; the experimentally supported modern role of Sbp1 is cytoplasmic mRNA translation repression and P-body remodeling. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE Sources checked: PANTHER:PTN000543777 Β· PANTHER:PTN000543777 SUPPORTS SOURCE BUT NOT TARGET PTHR23003 places rRNA processing on PTN000543777 from other RRM-family evidence; SGD:S000006316 resolves to MRD1 but is absent from the local PTHR23003 member table, and the second donor is zebrafish. Sbp1 is in the SF56 subfamily and its branch has cytoplasmic mRNA-translation and P-body biology; its old nucleolar snRNP evidence does not directly support inheritance of an rRNA-processing role. Supporting Evidence: PMID:2121740 Since snR10 has been implicated in pre-rRNA processing, the association of SSB-1 and snR10 into a nucleolar snRNP particle indicates SSB-1 involvement in rRNA processing as well. |
| GO:0071028 nuclear mRNA surveillance | IBA GO_REF:0000033 | REMOVE | Summary: PTHR23003 now places nuclear mRNA surveillance on the same PTN000543777 node, but this process reflects other RRM-family descendants rather than Sbp1. The SBP1 evidence supports cytoplasmic mRNA binding, translation repression, P-body/stress-granule localization, and P-body disassembly, not nuclear mRNA surveillance. Reason: The PTN000543777 nuclear-process placement appears to over-propagate from paralogous SF3 RRM proteins across the functionally divergent SBP1/SF56 branch. Sbp1's accepted mRNA-regulatory function acts in cytoplasmic mRNP translation/storage control and P-body remodeling; neither the cached SBP1 literature nor UniProt supports a nuclear mRNA-surveillance role. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE Sources checked: PANTHER:PTN000543777 Β· PANTHER:PTN000543777 SUPPORTS SOURCE BUT NOT TARGET PTHR23003 places nuclear mRNA surveillance on PTN000543777 from the SF3 GBP2/HRB1/RRM75 branch, while Sbp1 is in SF56; the SBP1 branch has cytoplasmic mRNA-translation and P-body biology, and the cached SBP1 literature does not support inheritance of this nuclear process. Supporting Evidence: PMID:39617253 the binding of Sbp1 to the 5'UTRs of mRNAs represses both cap-dependent and cap-independent translation initiation of proteins |
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Download this section (compressed HTML)Q: Does Sbp1 disassemble P-bodies primarily by sequestering Edc3 from Edc3-Edc3 contacts, or does it also remodel RNA and other P-body scaffold interactions?
Q: How are Sbp1's historical nucleolar association with snR10/snR11 and its contemporary cytoplasmic translation-control functions partitioned across growth conditions?
Experiment: Compare P-body disassembly kinetics after stress recovery in strains expressing separation-of-function Sbp1 variants that disrupt the RRM domains, the RGG motif, or mapped Edc3-contact surfaces, using endogenous Edc3/Dhh1/Scd6 markers.
Hypothesis: Sbp1's Edc3-binding activity is sufficient to drive P-body dissolution independently of its mRNA-binding activity.
Type: live-cell imaging and separation-of-function mutagenesis
Experiment: Quantify endogenously tagged Sbp1 together with nucleolar, P-body, and stress-granule markers across logarithmic growth, glucose deprivation, and recovery, and pair the imaging with snR10/snR11 and mRNA interaction measurements.
Hypothesis: The nucleolar and cytoplasmic pools of Sbp1 represent regulated, condition-specific functions rather than conflicting localization assignments.
Type: quantitative microscopy and RNA co-immunoprecipitation
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Download this section (compressed HTML)mRNA-binding translational repressor and P-body disassembly factor; binds to the 5'UTR of mRNAs and inhibits cap-dependent and independent translational initiation; involved in mRNA binding under glucose starvation stress; associates with snR10 and snR11; HMT1-dependent arginine monomethylation modulates translational repression, mRNA decay and stress granule localization during glucose starvation; contains an intrinsically disordered RGG motif; localizes to P bodies and stress granules
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