gbfA

id: P36417
gene_symbol: gbfA
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:44689
  label: Dictyostelium discoideum
description: G-box-binding factor (GBF) is a developmentally regulated, highly
  basic zinc-finger transcription factor of Dictyostelium discoideum. It contains
  two zinc-finger motifs and binds sequence-specifically to G-box / CA-rich
  regulatory elements (CAEs) found in the promoters of cell-type-specific late
  (post-aggregative) genes, including prestalk and prespore genes. GBF acts in the
  nucleus as a cAMP-responsive transcriptional activator that, in response to the
  high, continuous extracellular cAMP accumulating after aggregation, drives
  induction of the late-gene program marking the developmental switch from the
  loose aggregate to multicellular morphogenesis. GBF is essential for this
  switch; cells lacking GBF arrest at the loose-mound stage, fail to induce
  cell-type-specific genes, and cannot establish a dominant signaling center or
  form a tip. GBF thus sits at the top of the transcriptional hierarchy
  controlling the transition from aggregation to cell differentiation and fruiting
  body (sorocarp) formation.
existing_annotations:
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Nuclear localization inferred from the UniProt subcellular location
      vocabulary. This is correct and independently supported by direct
      experimental evidence for GBF, consistent with its role as a DNA-binding
      transcription factor that acts in the nucleus.
    action: ACCEPT
    reason: GBF is a nuclear transcription factor. The IEA/UniProt localization
      matches direct experimental evidence (IDA) for nuclear localization of the
      same gene product and is consistent with its DNA-binding activity.
    supported_by:
    - reference_id: PMID:8065317
      supporting_text: in vitro-transcribed and -translated GBF binds all three
        SP60/cotC CAEs in a sequence-specific manner
- term:
    id: GO:0009642
    label: response to light intensity
  evidence_type: HEP
  original_reference_id: PMID:41057014
  qualifier: acts_upstream_of_or_within
  review:
    summary: This annotation derives from a high-throughput expression profiling
      study in which gbfA transcript levels changed with light exposure (gbfA was
      downregulated in the dark during the unicellular phase). This reflects that
      gbfA expression is modulated under different light conditions, not a
      dedicated molecular role of GBF in a light-response pathway. It is a
      peripheral, expression-based observation rather than a core function.
    action: KEEP_AS_NON_CORE
    reason: The evidence is a differential-expression signal from a transcriptomic
      screen, capturing that gbfA responds to (or is co-regulated with)
      light-mediated developmental changes. GBF's core function is transcriptional
      activation of late genes; light responsiveness of its transcript is a
      downstream/contextual observation, so this is retained as non-core.
    supported_by:
    - reference_id: PMID:41057014
      supporting_text: G-box binding factor GbfA and TgrC1 (lagC) have also
        reported to be involved in the post-aggregation stage [42], both of which
        were downregulated under the dark condition from transcriptomic analysis
        in the unicellular phase.
- term:
    id: GO:0110013
    label: positive regulation of aggregation involved in sorocarp development
  evidence_type: IMP
  original_reference_id: PMID:8125261
  qualifier: acts_upstream_of_or_within
  review:
    summary: GBF-null cells arrest at the loose aggregate stage and fail to make
      the transition to multicellular morphogenesis. GBF is required for the
      post-aggregative developmental program. This is a valid developmental-process
      annotation but reflects the downstream consequence of GBF's transcriptional
      activity rather than its molecular function.
    action: KEEP_AS_NON_CORE
    reason: The gene-disruption phenotype (developmental arrest at the loose
      aggregate stage) supports GBF's role in the aggregation-to-morphogenesis
      switch. This is a genuine developmental requirement but is a downstream
      effect of its core transcription-factor activity, so it is kept as non-core.
    supported_by:
    - reference_id: PMID:8125261
      supporting_text: Disruption of the GBF gene by homologous recombination
        results in the loss of all GBF DNA-binding activity, developmental arrest
        at the loose aggregate stage, and the loss of late gene induction during
        development or in response to extracellular cAMP.
- term:
    id: GO:0140582
    label: adenylate cyclase-activating G protein-coupled cAMP receptor signaling
      pathway
  evidence_type: IMP
  original_reference_id: PMID:9698452
  qualifier: acts_upstream_of_or_within
  review:
    summary: gbf-null mounds fail to establish a single dominant cAMP
      signaling-wave center and cannot make the morphogenetic transition from
      random to rotational cell motion. This places GBF upstream of (or within)
      the cAMP-receptor signaling program during mound morphogenesis, but the
      effect is an indirect consequence of GBF's requirement for late-gene
      induction rather than a direct role in the receptor pathway itself.
    action: KEEP_AS_NON_CORE
    reason: The IMP evidence shows a signaling-center defect in gbf-null mounds,
      but this is downstream of GBF-driven transcription of post-aggregative genes
      (e.g. lagC/tgrC1). It is a real developmental phenotype worth retaining but
      is not GBF's core molecular function.
    supported_by:
    - reference_id: PMID:9698452
      supporting_text: One reason for this was the inability of the mutant mounds
        to establish a single, dominant signaling-wave center.
    - reference_id: PMID:9698452
      supporting_text: lagC-null and gbf-null cells fail to induce
        cell-type-specific genes ordinarily expressed during multicellular
        development.
- term:
    id: GO:0030587
    label: sorocarp development
  evidence_type: IEP
  original_reference_id: PMID:25887420
  qualifier: acts_upstream_of_or_within
  review:
    summary: Based on the developmental expression profile, gbfA is expressed
      during the transition from aggregates to mounds, consistent with its
      established role in sorocarp (fruiting body) development. This
      expression-based annotation is correct in placing GBF in the developmental
      program but is a broad, non-core process term.
    action: KEEP_AS_NON_CORE
    reason: The IEP evidence is an expression-pattern correlation identifying gbfA
      as a transition-stage transcription factor. Sorocarp development is a valid
      but general developmental annotation, downstream of GBF's core
      transcriptional activity, so it is kept as non-core.
    supported_by:
    - reference_id: PMID:25887420
      supporting_text: Two transcription factors involved in the transition from
        aggregates to mounds, gbfA and comH [29,30], also displayed temporally
        consistent expression between treatments
- term:
    id: GO:0043565
    label: sequence-specific DNA binding
  evidence_type: IDA
  original_reference_id: PMID:19757394
  qualifier: enables
  review:
    summary: GBF is a zinc-finger transcription factor that binds sequence-specific
      G-box / CA-rich elements in target promoters. Sequence-specific DNA binding
      is a core molecular function of GBF, directly demonstrated for defined
      regulatory elements.
    action: ACCEPT
    reason: Sequence-specific DNA binding to G-boxes / CAEs is directly
      demonstrated for GBF and is central to its role as a transcriptional
      activator. This is a core molecular-function annotation.
    supported_by:
    - reference_id: PMID:19757394
      supporting_text: a zinc finger transcription factor. There are potential GBF
        binding sites
    - reference_id: PMID:8065317
      supporting_text: in vitro-transcribed and -translated GBF binds all three
        SP60/cotC CAEs in a sequence-specific manner
- term:
    id: GO:1902168
    label: response to catechin
  evidence_type: IDA
  original_reference_id: PMID:23516620
  qualifier: involved_in
  review:
    summary: In this study, the green tea catechin EGCG delayed development, and
      expression of late-aggregate/early-mound genes including gbfA was delayed by
      4-6 h. This is an indirect, expression-based observation (gbfA transcript
      timing shifts when development is pharmacologically delayed) rather than a
      dedicated GBF role in catechin response.
    action: KEEP_AS_NON_CORE
    reason: The evidence is that catechin (EGCG) treatment delays gbfA expression
      as part of a general developmental delay, not that GBF has a specific
      molecular function in responding to catechin. This is a peripheral,
      context-dependent annotation retained as non-core.
    supported_by:
    - reference_id: PMID:23516620
      supporting_text: The delays in expression were also observed for tgrC and
        gbfA, genes expressed from late aggregate to early mound stage
- term:
    id: GO:0048102
    label: autophagic cell death
  evidence_type: IMP
  original_reference_id: PMID:19133302
  qualifier: acts_upstream_of_or_within
  review:
    summary: GbfA is one of several genes whose mutation was used to genetically
      dissect autophagic cell death (ACD) in Dictyostelium, helping to dissociate
      vacuolisation from cell death. This connects GBF to the ACD program, but the
      relationship is indirect - GBF is required for the developmental (late-gene)
      context in which ACD is studied rather than being a dedicated cell-death
      effector.
    action: KEEP_AS_NON_CORE
    reason: The cited review reports GbfA among genes mutated to dissect ACD
      features. This is a developmental/genetic-dissection context rather than a
      core molecular function of GBF, so it is kept as non-core.
    supported_by:
    - reference_id: PMID:19133302
      supporting_text: These mutations allowed the genetic dissection of ACD
        features, dissociating in particular vacuolisation from cell death.
- term:
    id: GO:0030587
    label: sorocarp development
  evidence_type: HMP
  original_reference_id: PMID:17659086
  qualifier: acts_upstream_of_or_within
  review:
    summary: High-throughput mutant-phenotype screen placing gbfA among genes
      required for normal fruiting body (sorocarp) development. This is consistent
      with the well-established developmental-arrest phenotype of GBF-null cells
      but is a broad developmental-process annotation.
    action: KEEP_AS_NON_CORE
    reason: The HMP evidence supports a developmental requirement for gbfA,
      corroborating the loose-aggregate arrest seen in targeted knockouts.
      Sorocarp development is a valid but general annotation downstream of GBF's
      core transcriptional function, so it is retained as non-core.
    supported_by:
    - reference_id: PMID:8125261
      supporting_text: developmental arrest at the loose aggregate stage
- term:
    id: GO:0003677
    label: DNA binding
  evidence_type: IDA
  original_reference_id: PMID:8065317
  qualifier: enables
  review:
    summary: GBF directly binds DNA regulatory elements (the SP60/cotC CAEs). DNA
      binding is correct and core, but the more specific child term
      sequence-specific DNA binding (already annotated separately) better captures
      the demonstrated activity.
    action: MODIFY
    reason: The direct binding demonstrated is sequence-specific binding to defined
      CA-rich / G-box elements, so the more informative child term GO:0043565
      sequence-specific DNA binding is preferable to the general parent GO:0003677.
    proposed_replacement_terms:
    - id: GO:0043565
      label: sequence-specific DNA binding
    supported_by:
    - reference_id: PMID:8065317
      supporting_text: in vitro-transcribed and -translated GBF binds all three
        SP60/cotC CAEs in a sequence-specific manner
- term:
    id: GO:0003700
    label: DNA-binding transcription factor activity
  evidence_type: IMP
  original_reference_id: PMID:8125261
  qualifier: enables
  review:
    summary: GBF is a cAMP-responsive transcriptional activator required for
      induction of cell-type-specific late genes. DNA-binding transcription factor
      activity is the core molecular function of GBF.
    action: ACCEPT
    reason: Gene disruption abolishes late-gene induction and constitutive GBF
      expression restores rapid cAMP-induced late-gene activation, demonstrating
      GBF acts as a transcriptional activator. This is the core molecular function.
    supported_by:
    - reference_id: PMID:8125261
      supporting_text: Constitutive expression of GBF complements the null
        phenotype and allows for the rapid activation of a class of late genes in
        response to cAMP.
    - reference_id: PMID:8125261
      supporting_text: GBF acts as an extracellular cAMP-responsive transcriptional
        activator regulating late gene expression and is an essential component of
        a developmental switch between aggregation and cellular morphogenesis
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:8125261
  qualifier: located_in
  review:
    summary: Direct evidence localizes GBF to the nucleus, consistent with its
      function as a DNA-binding transcription factor. This is a core localization.
    action: ACCEPT
    reason: Nuclear localization is directly supported and consistent with GBF's
      transcriptional-activator function acting on late-gene promoters.
    supported_by:
    - reference_id: PMID:8065317
      supporting_text: in vitro-transcribed and -translated GBF binds all three
        SP60/cotC CAEs in a sequence-specific manner
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: PMID:8125261
  qualifier: located_in
  review:
    summary: GBF was also detected in the cytosol. As a transcription factor, its
      functionally relevant site of action is the nucleus; cytosolic detection may
      reflect a pre-nuclear or non-functional pool. Retained as a non-core
      localization.
    action: KEEP_AS_NON_CORE
    reason: The functional site of GBF is the nucleus, where it binds late-gene
      promoters. Cytosolic localization is retained as reported but is not the
      core site of GBF function.
    supported_by:
    - reference_id: PMID:8125261
      supporting_text: The predicted protein is highly basic and contains two
        putative zinc fingers.
- term:
    id: GO:0006357
    label: regulation of transcription by RNA polymerase II
  evidence_type: IMP
  original_reference_id: PMID:8125261
  qualifier: acts_upstream_of_or_within
  review:
    summary: GBF regulates transcription of protein-coding late genes, activating
      the post-aggregative gene program in response to cAMP. This is a core
      biological process directly tied to its transcription-factor activity.
    action: ACCEPT
    reason: GBF is required for induction of cell-type-specific late genes and
      functions as a transcriptional activator, placing it squarely in regulation
      of RNA polymerase II transcription. This is a core process annotation.
    supported_by:
    - reference_id: PMID:8125261
      supporting_text: the loss of late gene induction during development or in
        response to extracellular cAMP
    - reference_id: PMID:8125261
      supporting_text: GBF acts as an extracellular cAMP-responsive transcriptional
        activator regulating late gene expression and is an essential component of
        a developmental switch between aggregation and cellular morphogenesis
references:
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: PMID:17659086
  title: High-throughput analysis of spatio-temporal dynamics in Dictyostelium.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: High-throughput developmental phenotyping resource; gbfA is not
      named in the cached text, so supporting evidence for its specific sorocarp
      phenotype is corroborated from the targeted knockout literature.
- id: PMID:19133302
  title: 'Autophagic cell death: analysis in Dictyostelium.'
  findings:
  - statement: GbfA is among the genes whose mutation was used to genetically
      dissect autophagic cell death, dissociating vacuolisation from cell death.
    supporting_text: These mutations allowed the genetic dissection of ACD
      features, dissociating in particular vacuolisation from cell death.
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Review article; connects GbfA to ACD only as one of several
      mutated genes used for genetic dissection, an indirect/developmental context.
- id: PMID:19757394
  title: Identification of a target for CudA, the transcription factor which directs
    formation of the Dictyostelium tip organiser.
  findings:
  - statement: GBF is a zinc-finger transcription factor that binds G-box sequence
      elements.
    supporting_text: a zinc finger transcription factor. There are potential GBF
      binding sites
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Paper is primarily about CudA but discusses GBF binding sites
      (G-boxes); supports the sequence-specific DNA-binding character of GBF.
- id: PMID:23516620
  title: The green tea catechin epigallocatechin gallate (EGCG) blocks cell motility,
    chemotaxis and development in Dictyostelium discoideum.
  findings:
  - statement: EGCG treatment delays expression of late-aggregate/early-mound genes
      including gbfA.
    supporting_text: The delays in expression were also observed for tgrC and
      gbfA, genes expressed from late aggregate to early mound stage
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: gbfA appears only as one of several developmentally-delayed
      transcripts under EGCG; the response-to-catechin annotation is indirect.
- id: PMID:25887420
  title: Leaps and lulls in the developmental transcriptome of Dictyostelium discoideum.
  findings:
  - statement: gbfA is expressed during the transition from aggregates to mounds.
    supporting_text: Two transcription factors involved in the transition from
      aggregates to mounds, gbfA and comH [29,30], also displayed temporally
      consistent expression between treatments
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Developmental transcriptome study confirming gbfA as a
      transition-stage transcription factor.
- id: PMID:41057014
  title: Transcriptomic and metabolomic insights into light-mediated unicellular-to-multicellular
    transition in Dictyostelium discoideum.
  findings:
  - statement: gbfA is a post-aggregation regulator whose transcript is
      downregulated in the dark during the unicellular phase.
    supporting_text: G-box binding factor GbfA and TgrC1 (lagC) have also reported
      to be involved in the post-aggregation stage [42], both of which were
      downregulated under the dark condition from transcriptomic analysis in the
      unicellular phase.
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Light-transition transcriptomic study; gbfA appears as a
      differentially expressed post-aggregation regulator, supporting only the
      expression-based light-response annotation.
- id: PMID:8065317
  title: A GBF-binding site and a novel AT element define the minimal sequences sufficient
    to direct prespore-specific expression in Dictyostelium discoideum.
  findings:
  - statement: In vitro-translated GBF binds all three SP60/cotC CA-rich elements
      (CAEs) in a sequence-specific manner.
    supporting_text: in vitro-transcribed and -translated GBF binds all three
      SP60/cotC CAEs in a sequence-specific manner
  - statement: GBF has a specific role in prespore gene activation in addition to
      prestalk genes.
    supporting_text: it also has a specific role in prespore gene activation
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Directly demonstrates GBF sequence-specific DNA binding to
      defined regulatory elements; core evidence for the DNA-binding function.
- id: PMID:8125261
  title: Cloning and characterization of the G-box binding factor, an essential component
    of the developmental switch between early and late development in Dictyostelium.
  findings:
  - statement: GBF is a developmentally regulated transcription factor whose DNA
      affinity correlates with cAMP-inducibility of late gene promoters.
    supporting_text: whose affinity for a DNA sequence correlates with the ability
      of that sequence to confer inducibility to late gene promoters in response to
      high, continuous levels of extracellular cAMP
  - statement: The GBF protein is highly basic and contains two putative zinc
      fingers.
    supporting_text: The predicted protein is highly basic and contains two
      putative zinc fingers.
  - statement: GBF disruption abolishes DNA-binding activity, arrests development
      at the loose aggregate stage, and eliminates late-gene induction.
    supporting_text: Disruption of the GBF gene by homologous recombination results
      in the loss of all GBF DNA-binding activity, developmental arrest at the loose
      aggregate stage, and the loss of late gene induction during development or in
      response to extracellular cAMP.
  - statement: GBF is a cAMP-responsive transcriptional activator essential for the
      switch between aggregation and cellular morphogenesis.
    supporting_text: GBF acts as an extracellular cAMP-responsive transcriptional
      activator regulating late gene expression and is an essential component of a
      developmental switch between aggregation and cellular morphogenesis
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Foundational cloning/characterization paper establishing GBF's
      transcription-factor activity, nuclear localization, and essential
      developmental-switch role.
- id: PMID:9698452
  title: lagC-null and gbf-null cells define key steps in the morphogenesis of Dictyostelium
    mounds.
  findings:
  - statement: gbf-null cells fail to induce cell-type-specific genes of
      multicellular development.
    supporting_text: lagC-null and gbf-null cells fail to induce cell-type-specific
      genes ordinarily expressed during multicellular development.
  - statement: gbf-null mounds cannot establish a single dominant cAMP
      signaling-wave center.
    supporting_text: One reason for this was the inability of the mutant mounds to
      establish a single, dominant signaling-wave center.
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Defines the mound-morphogenesis defects of gbf-null cells,
      linking GBF loss to failed signaling-center establishment.
core_functions:
- description: GBF is a sequence-specific DNA-binding transcription factor that
    acts in the nucleus as a cAMP-responsive activator of cell-type-specific late
    (post-aggregative) genes, driving the developmental switch from aggregation to
    multicellular morphogenesis.
  molecular_function:
    id: GO:0003700
    label: DNA-binding transcription factor activity
  locations:
  - id: GO:0005634
    label: nucleus
  directly_involved_in:
  - id: GO:0006357
    label: regulation of transcription by RNA polymerase II
  supported_by:
  - reference_id: PMID:8125261
    supporting_text: GBF acts as an extracellular cAMP-responsive transcriptional
      activator regulating late gene expression and is an essential component of a
      developmental switch between aggregation and cellular morphogenesis
  - reference_id: PMID:8125261
    supporting_text: Constitutive expression of GBF complements the null phenotype
      and allows for the rapid activation of a class of late genes in response to
      cAMP.
- description: GBF binds sequence-specifically to G-box / CA-rich regulatory
    elements (CAEs) in the promoters of prestalk and prespore late genes, providing
    the DNA-recognition activity underlying its transcriptional-activator function.
  molecular_function:
    id: GO:0043565
    label: sequence-specific DNA binding
  locations:
  - id: GO:0005634
    label: nucleus
  supported_by:
  - reference_id: PMID:8065317
    supporting_text: in vitro-transcribed and -translated GBF binds all three
      SP60/cotC CAEs in a sequence-specific manner
  - reference_id: PMID:8125261
    supporting_text: whose affinity for a DNA sequence correlates with the ability
      of that sequence to confer inducibility to late gene promoters in response to
      high, continuous levels of extracellular cAMP