SOC1

UniProt ID: O64645
Organism: Arabidopsis thaliana
Review Status: COMPLETE
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Gene Description

SOC1/AGL20 encodes a 214 aa MIKC-type MADS-box transcription factor in Arabidopsis thaliana. It is a nuclear, sequence-specific RNA polymerase II transcription regulator that integrates photoperiod, vernalization/FLC, gibberellin, and age-related flowering signals at the shoot apical meristem. SOC1 promotes the vegetative-to-reproductive meristem transition by forming MADS-domain partner complexes, especially with AGL24, and by directly regulating flowering and floral-transition targets such as LFY, AGL24, and TFS1. SOC1 can be observed in the cytoplasm when expressed alone, but AGL24 interaction promotes nuclear accumulation, consistent with partner-dependent MADS transcription factor function.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0009409 response to cold
IEP
PMID:16507079
Quantitative effects of vernalization on FLC and SOC1 expres...
KEEP AS NON CORE
Summary: The source supports SOC1 transcript induction by vernalization/cold in reciprocal relationship to FLC repression. This is useful evidence that SOC1 is an output of cold-dependent flowering regulation, but it does not make cold response the core function of the protein.
Reason: PMID:16507079 directly reports quantitative and acute SOC1 induction after cold exposure. Expression change is a valid response claim; direct temperature sensing or a generalized freezing-tolerance role is not required or inferred. Retain as non-core input/context relative to transcriptional control of flowering.
Supporting Evidence:
PMID:16507079
SUPPRESSOR OF OVER-EXPRESSION OF CO 1 (SOC1), a downstream target of FLC, is quantitatively induced by vernalization in a reciprocal manner to FLC.
GO:0009908 flower development
TAS
PMID:10995392
The AGAMOUS-LIKE 20 MADS domain protein integrates floral in...
MODIFY
Summary: Specify SOC1's positive regulation of flower development.
Reason: PMID:10995392 identifies AGL20/SOC1 as a dominant FRI suppressor and shows that its overexpression suppresses late flowering. GO:0009911 captures SOC1's positive regulatory role in floral development. This is a lateral role correction from flower development to its positive regulation, not an is_a/part_of descendant refinement; the separate meristem-transition process remains supported.
Supporting Evidence:
PMID:11123798
By transposon tagging we have identified late flowering agl20 mutants, showing that AGL20 is involved in flowering time control.
PMID:18466303
SOC1 directly binds to the distal and proximal region of the LFY promoter where critical cis-elements are located.
PMID:10995392
Overexpression of AGL20 suppresses not only the late flowering of plants that have functional FRI and FLC alleles but also the delayed phase transitions during the vegetative stages of plant development.
GO:0009911 positive regulation of flower development
IMP
PMID:10834834
Distinct roles of CONSTANS target genes in reproductive deve...
ACCEPT
Summary: SOC1 promotes flower development.
Reason: PMID:10834834 identifies SOC1 as an early CONSTANS target required for CO-mediated flowering promotion. That positive genetic role, together with independent SOC1 target-regulatory evidence, supports retaining positive regulation of flower development. The related meristem-transition annotation does not replace this valid regulatory claim.
Supporting Evidence:
PMID:11123798
By transposon tagging we have identified late flowering agl20 mutants, showing that AGL20 is involved in flowering time control.
PMID:18466303
SOC1 directly binds to the distal and proximal region of the LFY promoter where critical cis-elements are located.
PMID:10834834
Two of these genes, SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) and FLOWERING LOCUS T (FT), are required for CO to promote flowering; the others are involved in proline or ethylene biosynthesis.
GO:0009911 positive regulation of flower development
IMP
PMID:11123798
A MADS domain gene involved in the transition to flowering i...
ACCEPT
Summary: SOC1 promotes flower development.
Reason: PMID:11123798 reports late-flowering agl20 mutants and photoperiod-independent flowering after constitutive AGL20 expression in Arabidopsis. These complementary perturbations establish SOC1 as a positive regulator of flowering, supporting this signed process rather than only an association with developmental timing.
Supporting Evidence:
PMID:11123798
By transposon tagging we have identified late flowering agl20 mutants, showing that AGL20 is involved in flowering time control.
PMID:18466303
SOC1 directly binds to the distal and proximal region of the LFY promoter where critical cis-elements are located.
GO:0010077 maintenance of inflorescence meristem identity
IGI
PMID:20626659
Arabidopsis BLADE-ON-PETIOLE1 and 2 promote floral meristem ...
KEEP AS NON CORE
Summary: IGI (with BOP1/BOP2) for maintenance of inflorescence meristem identity, from a study showing that BOP1/2, LFY and AP1 converge to down-regulate flowering-time MADS genes in floral meristems. The cached abstract names AGL24 rather than SOC1; the genetic interaction with soc1 is in the full text, which is not cached.
Reason: SOC1, with AGL24 and SVP, promotes inflorescence (shoot) character and must be repressed in floral primordia for floral meristem identity, so a role in maintaining inflorescence meristem identity is biologically consistent. The quoted abstract sentence gives the pathway context but does not name SOC1; the SOC1 genetic interaction is in the full text, which is not cached. The experimental curator saw the full text; the annotation is retained but treated as non-core relative to SOC1's floral-integrator role in the vegetative-to-reproductive transition.
Supporting Evidence:
PMID:20626659
Our data show that BOP1/2 function distinctly from LFY to upregulate AP1 in floral primordia and that all three activities converge to down-regulate flowering-time regulators including AGAMOUS-LIKE24 in stage 2 floral meristems.
GO:0000977 RNA polymerase II transcription regulatory region sequence-specific DNA binding
IEA
GO_REF:0000002
ACCEPT
Summary: SOC1 is a MADS-box transcription factor, and direct studies show SOC1 binding to regulatory DNA regions such as the LFY promoter and CArG-box regions at TFS1.
Reason: This sequence-specific RNA polymerase II regulatory-region DNA-binding activity is consistent with conserved MADS-box domains and with direct SOC1 promoter-binding evidence.
Supporting Evidence:
PMID:18466303
Here, we show that SOC1 directly binds to the distal and proximal region of the LFY promoter where critical cis-elements are located.
GO:0000978 RNA polymerase II cis-regulatory region sequence-specific DNA binding
IBA
GO_REF:0000033
ACCEPT
Summary: The IBA annotation matches SOC1's conserved MADS-domain DNA-binding role and is supported by gene-specific ChIP/promoter evidence for LFY and TFS1 regulatory regions.
Reason: SOC1 is a sequence-specific cis-regulatory DNA-binding transcription factor acting on RNA polymerase II-transcribed genes.
Supporting Evidence:
PMID:30946745
ChIP-qPCR analysis of SOC1 (B) and SVP (C) on CArG-boxes at TFS1 in 35S::SOC1:GR soc1 plants after DEX treatment.
PMID:18466303
SOC1 directly binds to the distal and proximal region of the LFY promoter where critical cis-elements are located.
GO:0000981 DNA-binding transcription factor activity, RNA polymerase II-specific
IPI
PMID:30946745
Floral regulators FLC and SOC1 directly regulate expression ...
ACCEPT
Summary: Richter et al. place SOC1 as a MADS-box transcription factor that directly activates TFS1 and opposes Polycomb repression by recruiting REF6 and BRM. This supports RNA polymerase II-specific DNA-binding transcription factor activity.
Reason: SOC1 independently enables transcription factor activity through its MADS-domain DNA binding and transcriptional regulatory function at flowering-transition targets.
Supporting Evidence:
PMID:30946745
SOC1 opposes PRC function at TFS1 through recruitment of the histone demethylase RELATIVE OF EARLY FLOWERING 6 (REF6) and the SWI/SNF chromatin remodeler ATPase BRAHMA (BRM).
file:ARATH/SOC1/SOC1-deep-research-falcon.md
Primary molecular role is a **sequence-specific transcriptional regulator promoting floral transition**; SOC1 integrates endogenous and environmental flowering inputs and activates floral meristem identity programs
GO:0003677 DNA binding
IEA
GO_REF:0000002
MODIFY
Summary: SOC1 clearly binds DNA, but the generic DNA binding term loses the important specificity that SOC1 is a MADS-domain RNA polymerase II cis-regulatory transcription factor.
Reason: Replace generic DNA binding with RNA polymerase II cis-regulatory region sequence-specific DNA binding, which captures the MADS-box regulatory DNA-binding activity.
Supporting Evidence:
PMID:18466303
SOC1 directly binds to the distal and proximal region of the LFY promoter where critical cis-elements are located.
GO:0003700 DNA-binding transcription factor activity
IEA
GO_REF:0000002
MODIFY
Summary: The generic transcription factor activity term is directionally correct but less specific than the RNA polymerase II-specific activity supported for plant MADS-box transcription factors.
Reason: SOC1 regulates RNA polymerase II-transcribed developmental genes, so GO:0000981 is the better molecular-function term.
Supporting Evidence:
file:ARATH/SOC1/SOC1-uniprot.txt
Transcription activator active in flowering time control.
GO:0003700 DNA-binding transcription factor activity
TAS
PMID:10995392
The AGAMOUS-LIKE 20 MADS domain protein integrates floral in...
MODIFY
Summary: The paper supports SOC1/AGL20 as a MADS-domain flowering regulator. The molecular-function term should be the RNA polymerase II-specific transcription factor activity rather than the broader legacy term.
Reason: SOC1 acts as a MADS-box RNA polymerase II transcription factor in flowering control, and GO:0000981 captures that specificity.
Supporting Evidence:
PMID:10995392
A MADS-domain gene, AGAMOUS-LIKE 20 (AGL20), was identified as a dominant FRI suppressor in activation tagging mutagenesis.
PMID:10995392
Overexpression of AGL20 suppresses not only the late flowering of plants that have functional FRI and FLC alleles but also the delayed phase transitions during the vegetative stages of plant development.
GO:0003700 DNA-binding transcription factor activity
ISS
PMID:11118137
Arabidopsis transcription factors: genome-wide comparative a...
MODIFY
Summary: The source is a genome-wide transcription factor family analysis and is consistent with SOC1 being a transcription factor, but the annotation should use the more precise RNA polymerase II-specific term.
Reason: SOC1 is not merely any DNA-binding transcription factor; it is a eukaryotic MADS-domain regulator of RNA polymerase II target genes.
Supporting Evidence:
PMID:11118137
Arabidopsis dedicates over 5% of its genome to code for more than 1500 transcription factors
GO:0003700 DNA-binding transcription factor activity
ISS
PMID:11123798
A MADS domain gene involved in the transition to flowering i...
MODIFY
Summary: SOC1/AGL20 is described as a MADS-domain gene involved in floral induction. The activity is correct in essence but should be updated to the RNA polymerase II-specific transcription factor term.
Reason: The more precise molecular-function term is GO:0000981.
Supporting Evidence:
PMID:11123798
AGL20 (AGAMOUS LIKE 20) is a MADS domain gene from Arabidopsis that is activated in shoot apical meristems during the transition to flowering.
GO:0003700 DNA-binding transcription factor activity
ISS
PMID:12837945
Molecular and phylogenetic analyses of the complete MADS-box...
MODIFY
Summary: The MADS-box family analysis supports SOC1 family membership and transcription factor inference, but the generic term is less informative than RNA polymerase II-specific DNA-binding transcription factor activity.
Reason: Update the broad term to GO:0000981, consistent with SOC1's conserved MADS-domain role in regulation of RNA polymerase II target genes.
Supporting Evidence:
PMID:12837945
MADS-box transcription factors are key regulators of several plant development processes.
GO:0005515 protein binding
IPI
PMID:11439126
APETALA1 and SEPALLATA3 interact to promote flower developme...
MODIFY
Summary: SOC1 forms heteromeric MADS-protein associations.
Reason: The original AP1/CAL screen abstract foregrounds SEP3 and does not expose every SOC1 pair, so no original partner identity is inferred from that abstract alone. Independent full PMID:15805477 explicitly places SOC1 in heterodimer interactions with floral identity proteins, and PMID:18466303 resolves SOC1-AGL24 function. These target-specific data support the molecular refinement without claiming the original experiment assayed the AGL24 pair.
Supporting Evidence:
PMID:15805477
Surprisingly, SVP, SOC1, and AGL24 also interact directly with the floral organ identity proteins.
PMID:18466303
heterodimerization of SOC1 and AGL24 is a key mechanism in activating LFY expression.
GO:0005515 protein binding
IPI
PMID:15805477
Comprehensive interaction map of the Arabidopsis MADS Box tr...
MODIFY
Summary: SOC1 participates in the characterized MADS heterodimer network.
Reason: Full PMID:15805477 identifies SOC1 associations linking flower-induction and floral-organ-identity proteins and discusses the heterodimer mechanism. Refine generic binding without extrapolating every yeast interaction to an obligatory native complex.
Supporting Evidence:
PMID:15805477
Surprisingly, SVP, SOC1, and AGL24 also interact directly with the floral organ identity proteins.
PMID:18466303
heterodimerization of SOC1 and AGL24 is a key mechanism in activating LFY expression.
GO:0005515 protein binding
IPI
PMID:18466303
SOC1 translocated to the nucleus by interaction with AGL24 d...
MODIFY
Summary: SOC1 interaction with AGL24 is a key mechanism for nuclear localization and LFY activation. The evidence supports heterodimerization rather than the uninformative protein binding term.
Reason: Replace protein binding with protein heterodimerization activity for the SOC1-AGL24 MADS-domain complex.
Supporting Evidence:
PMID:18466303
heterodimerization of SOC1 and AGL24 is a key mechanism in activating LFY expression.
GO:0005515 protein binding
IPI
PMID:20129060
Pin1At encoding a peptidyl-prolyl cis/trans isomerase regula...
REMOVE
Summary: Pin1At interacts with phosphorylated SOC1 and AGL24 and regulates flowering through prolyl cis/trans isomerization of these transcription factors. This is biologically relevant, but generic protein binding is not an informative SOC1 molecular-function annotation.
Reason: The interaction is best retained in interaction/protein-modification records. GO:0005515 does not describe SOC1's actual activity, and no more specific SOC1-enabled MF term is justified by this interaction. Removal does not imply the Pin1At interaction is false; SOC1 is the isomerization substrate here and no SOC1-enabled activity follows from it.
Supporting Evidence:
PMID:20129060
Pin1At interacts with the phosphorylated AGL24 and SOC1 in vitro and with AGL24 and SOC1 in vivo
GO:0005515 protein binding
IPI
PMID:21798944
Evidence for network evolution in an Arabidopsis interactome...
MODIFY
Summary: SOC1 MADS-partner binding is supported as heterodimerization.
Reason: The original interactome paper documents the binary yeast two-hybrid method, while the AP1/FUL pair assignment comes from the curated annotation and is not independently exposed in the cached main text. Independent full PMID:15805477 places SOC1 among the floral MADS heterodimer network, and PMID:18466303 directly supports the SOC1-AGL24 mechanism. This combined evidence supports the molecular-function refinement without assigning native stoichiometry to every high-throughput pair.
Supporting Evidence:
PMID:15805477
The proteins AP1 and FUL could serve as hubs between the flower induction pathway comprising interacting proteins such as SVP, SOC1, and AGL24, and the floral organ identity proteins.
PMID:18466303
heterodimerization of SOC1 and AGL24 is a key mechanism in activating LFY expression.
PMID:21798944
We tested all pair-wise combinations of proteins encoded by these constructs (space 1) with an improved high-throughput binary interactome mapping pipeline based on the yeast two-hybrid (Y2H) system (fig. S2) (3, 4).
GO:0005515 protein binding
IPI
PMID:24714165
Phytoplasma effector SAP54 hijacks plant reproduction by deg...
REMOVE
Summary: SAP54 targets SOC1 physically, but bare protein binding is uninformative.
Reason: Full PMID:24714165 recovers SOC1 in SAP54-associated material and confirms interaction and destabilization in plant assays. These interactions are real; remove GO:0005515 only under the uninformative-binding exception. Being an effector target does not give SOC1 SAP54's degradation or pathogenic activity.
Supporting Evidence:
PMID:24714165
10xmyc-tagged AP1, SEP3, and SOC1 readily co-immunoprecipitate with GFP-tagged SAP54
GO:0005515 protein binding
IPI
PMID:31540691
OXIDATIVE STRESS 3 regulates drought-induced flowering throu...
REMOVE
Summary: OXS3 binds SOC1 and modulates drought-associated flowering output through AP1 promoter repression. The specific biology is regulatory, but the protein binding term remains too generic for SOC1's molecular function.
Reason: This interaction is non-core and should not be curated as generic protein binding. Existing SOC1 annotations to transcription factor activity and MADS heterodimerization better capture its function. Removal does not imply the OXS3 interaction is false; no informative SOC1-enabled molecular function follows from it.
Supporting Evidence:
PMID:31540691
OXS3 could bind SOC1 in vitro and in vivo.
GO:0046983 protein dimerization activity
IEA
GO_REF:0000002
MODIFY
Summary: Refine dimerization to the directly demonstrated SOC1-AGL24 heterodimerization.
Reason: SOC1 and AGL24 have experimentally established partner-dependent nuclear accumulation and LFY activation. This is more specific than generic dimerization and is already asserted by the supported MADS-partner interaction refinements.
Supporting Evidence:
PMID:18466303
heterodimerization of SOC1 and AGL24 is a key mechanism in activating LFY expression.
GO:0006355 regulation of DNA-templated transcription
IEA
GO_REF:0000002
MODIFY
Summary: SOC1 regulates transcription, but the existing term is broader than needed for a eukaryotic MADS-box transcription factor.
Reason: Replace with regulation of transcription by RNA polymerase II, which matches SOC1's nuclear transcriptional regulatory role.
Supporting Evidence:
file:ARATH/SOC1/SOC1-uniprot.txt
Transcription activator active in flowering time control.
GO:0006357 regulation of transcription by RNA polymerase II
IBA
GO_REF:0000033
ACCEPT
Summary: SOC1 is a conserved MADS-box transcription factor and direct studies show it regulates RNA polymerase II target genes during floral transition.
Reason: This biological process term appropriately captures SOC1's transcriptional regulatory role.
Supporting Evidence:
PMID:30946745
Furthermore, SOC1 directly activates the transcription of TFS1.
GO:0009739 response to gibberellin
IEP
PMID:18466303
SOC1 translocated to the nucleus by interaction with AGL24 d...
KEEP AS NON CORE
Summary: SOC1 participates in gibberellin-dependent flowering output through interaction with AGL24, but gibberellin response is an upstream hormonal input into the flowering network rather than SOC1's core molecular function.
Reason: The original paper is cached as an abstract that does not expose its complete GA experiments. Independent PMID:18339670 directly relates gibberellin-dependent flowering under short days to the AGL24-SOC1 interaction, and PMID:11123798 reports GA regulation of AGL20/SOC1. Retain the supported response as non-core; do not require SOC1 to be a hormone receptor or discard a true regulatory response because the readout is expression.
Supporting Evidence:
PMID:18339670
the effect of gibberellins on flowering under short-day conditions was mediated by the interaction between AGL24 and SOC1.
GO:0045893 positive regulation of DNA-templated transcription
IEP
PMID:18339670
Direct interaction of AGL24 and SOC1 integrates flowering si...
MODIFY
Summary: SOC1 directly upregulates AGL24 at the shoot apex in a positive-feedback loop. The annotation is correct in essence but should use the RNA polymerase II-specific positive regulation term.
Reason: Replace the broad DNA-templated transcription term with positive regulation of transcription by RNA polymerase II.
Supporting Evidence:
PMID:18339670
ChIP assay using a functional SOC1-9myc-tagged line and promoter mutagenesis analysis also revealed in vivo binding of SOC1-9myc to the regulatory regions of AGL24 and upregulation of AGL24 at the shoot apex by SOC1.
GO:0045944 positive regulation of transcription by RNA polymerase II
IEA
GO_REF:0000002
ACCEPT
Summary: SOC1 is described as a transcription activator and has gene-specific evidence for activation of AGL24, LFY, and TFS1-associated floral transition programs.
Reason: Positive regulation of RNA polymerase II transcription is a core aspect of SOC1's activity as a floral-transition transcription factor.
Supporting Evidence:
file:ARATH/SOC1/SOC1-uniprot.txt
Transcription activator active in flowering time control.
PMID:30946745
SOC1 directly activates the transcription of TFS1.
GO:0050793 regulation of developmental process
IEA
GO_REF:0000117
MODIFY
Summary: Specify positive regulation of flower development.
Reason: The electronic developmental-regulation claim is correctly refined to SOC1's directly established positive regulation of flowering, an existing descendant regulation term. This keeps the regulatory role explicit instead of replacing it with a different phase-transition process.
Supporting Evidence:
PMID:11123798
By transposon tagging we have identified late flowering agl20 mutants, showing that AGL20 is involved in flowering time control.
PMID:18466303
SOC1 directly binds to the distal and proximal region of the LFY promoter where critical cis-elements are located.
GO:0005634 nucleus
IEA
GO_REF:0000002
ACCEPT
Summary: SOC1's MADS transcription factor role requires nuclear activity, and direct localization experiments show AGL24-dependent nuclear relocation.
Reason: Nuclear localization is well supported for functional SOC1 transcription factor complexes.
Supporting Evidence:
PMID:18466303
The full-length SOC1 protein locates in the cytoplasm if expressed alone in protoplast transient expression assay, but relocates to the nucleus if expressed with AGAMOUS-LIKE 24 (AGL24)
GO:0005634 nucleus
IEA
GO_REF:0000044
ACCEPT
Summary: UniProt maps SOC1 to the nucleus based on curated subcellular-location evidence, consistent with direct SOC1-AGL24 localization experiments and transcription factor activity.
Reason: The nucleus is the primary site of SOC1's transcriptional regulatory function.
Supporting Evidence:
file:ARATH/SOC1/SOC1-uniprot.txt
Nucleus {ECO:0000255|PROSITE-ProRule:PRU00251, ECO:0000269|PubMed:18466303, ECO:0000269|PubMed:31540691}.
GO:0005634 nucleus
ISM
GO_REF:0000122
ACCEPT
Summary: AtSubP prediction is weaker than direct localization evidence, but the predicted nuclear localization agrees with SOC1's experimentally supported nuclear role.
Reason: Although the original evidence is computational, the term is supported by independent experimental localization and transcription-factor function.
Supporting Evidence:
PMID:18466303
The full-length SOC1 protein locates in the cytoplasm if expressed alone in protoplast transient expression assay, but relocates to the nucleus if expressed with AGAMOUS-LIKE 24 (AGL24)
GO:0005634 nucleus
IDA
PMID:18466303
SOC1 translocated to the nucleus by interaction with AGL24 d...
ACCEPT
Summary: SOC1 relocates to the nucleus when co-expressed with AGL24, consistent with partner-dependent nuclear action of SOC1-AGL24 MADS complexes.
Reason: Direct localization assays support nucleus as the functional site of SOC1 transcription factor activity.
Supporting Evidence:
PMID:18466303
The full-length SOC1 protein locates in the cytoplasm if expressed alone in protoplast transient expression assay, but relocates to the nucleus if expressed with AGAMOUS-LIKE 24 (AGL24)
GO:0005634 nucleus
IDA
PMID:31540691
OXIDATIVE STRESS 3 regulates drought-induced flowering throu...
ACCEPT
Summary: The cached abstract supports OXS3-SOC1 binding but does not describe localization. UniProt records OXS3 interaction with SOC1 in the nucleus, and other direct SOC1 localization evidence supports the nuclear term.
Reason: The term is correct for SOC1, but the source-specific localization detail is not present in the abstract-level cached publication.
Supporting Evidence:
file:ARATH/SOC1/SOC1-uniprot.txt
Interacts with OXS3 in the nucleus (PubMed:31540691).
PMID:31540691
OXS3 could bind SOC1 in vitro and in vivo.
GO:0005737 cytoplasm
IEA
GO_REF:0000044
KEEP AS NON CORE
Summary: SOC1 can be detected in the cytoplasm when expressed alone, while AGL24 interaction promotes relocation to the nucleus.
Reason: Cytoplasmic localization is experimentally observed, but the core site of SOC1 function is the nucleus. Retain as a context-dependent/non-core localization.
Supporting Evidence:
PMID:18466303
The full-length SOC1 protein locates in the cytoplasm if expressed alone in protoplast transient expression assay, but relocates to the nucleus if expressed with AGAMOUS-LIKE 24 (AGL24)
GO:0005737 cytoplasm
IDA
PMID:18466303
SOC1 translocated to the nucleus by interaction with AGL24 d...
KEEP AS NON CORE
Summary: Direct assays show cytoplasmic localization of full-length SOC1 when expressed alone in protoplasts, followed by nuclear relocalization in the presence of AGL24.
Reason: The cytoplasm term is supported as an observed localization state, but it is not the primary compartment for SOC1's transcriptional function.
Supporting Evidence:
PMID:18466303
The full-length SOC1 protein locates in the cytoplasm if expressed alone in protoplast transient expression assay, but relocates to the nucleus if expressed with AGAMOUS-LIKE 24 (AGL24)

Core Functions

SOC1 is a nuclear MADS-box RNA polymerase II transcription factor that binds cis-regulatory regions of floral-transition genes and activates transcriptional programs promoting the vegetative-to-reproductive meristem transition. Direct targets and outputs include AGL24 positive feedback, LFY promoter activation, and TFS1 activation with recruitment of chromatin regulators REF6 and BRM.

Supporting Evidence:
  • PMID:18466303
    SOC1 directly binds to the distal and proximal region of the LFY promoter where critical cis-elements are located.
  • PMID:18339670
    positive-feedback loop conferred by direct transcriptional regulation between AGL24 and SOC1 at the shoot apex integrates flowering signals.
  • PMID:30946745
    SOC1 opposes PRC function at TFS1 through recruitment of the histone demethylase RELATIVE OF EARLY FLOWERING 6 (REF6) and the SWI/SNF chromatin remodeler ATPase BRAHMA (BRM).

SOC1 forms MADS-domain partner complexes, most clearly a SOC1-AGL24 heterodimer, that regulate SOC1 nuclear accumulation and enable floral transition target activation. This dimerization/heterodimerization is a core mechanism but should be interpreted in the context of SOC1's transcription factor activity, not as generic protein binding.

Supporting Evidence:
  • PMID:18466303
    heterodimerization of SOC1 and AGL24 is a key mechanism in activating LFY expression.
  • file:ARATH/SOC1/SOC1-uniprot.txt
    Forms a heterodimer with AGL24 through MADS-box domain.

References

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Suggested Questions for Experts

Q: Which cold- and gibberellin-responsive SOC1 outputs reflect upstream control of flowering, and which involve additional physiological responses? How should those contexts be distinguished while retaining the supported response annotations?

Suggested experts: Coupland G, Lee I, Yu H

Q: Which SOC1 genotypes and meristem stages in PMID:20626659 support maintenance of inflorescence meristem identity, and how do they distinguish maintenance of shoot identity from promotion of the initial floral transition?

Suggested experts: Hepworth SR, Yu H

Q: Do native SOC1/AGL24 and related MIKC-type MADS assemblies have sufficiently stable composition and distinct functions to warrant more specific transcription-factor-complex terms beyond their established heterodimerization activity?

Suggested experts: Angenent GC, Immink RG, Coupland G

Q: Does the 2024 SOC1/AGL24 root-development study identified in the research report establish a direct regulatory contribution warranting a separate non-core annotation, and how does it distinguish root-specific activity from systemic flowering effects?

Suggested experts: Alvarez-Buylla ER, Garay-Arroyo A

Q: How do native SOC1 partner composition and cell type determine transcriptional activation versus repression during floral transition?

Q: Does the partner-dependent cytoplasmic-to-nuclear redistribution observed in transient protoplast assays occur with endogenous SOC1 in intact shoot meristems?

Suggested Experiments

Experiment: Perform native-promoter SOC1 CUT&RUN or ChIP-seq together with partner-specific perturbations of AGL24, SVP, AP1, and SPL factors, paired with nascent RNA-seq across the floral transition.

Hypothesis: SOC1 partner identity determines which floral-transition targets are activated at distinct shoot-apex stages.

Type: chromatin binding and transcriptional profiling

Experiment: Quantify native SOC1-GFP localization dynamics under long-day, short-day, vernalization, and gibberellin treatments in wild type and agl24 mutants.

Hypothesis: The cytoplasmic SOC1 pool is a regulated reservoir that becomes nuclear only after partner availability or signaling-dependent modification.

Type: live imaging

Experiment: Map SOC1 binding and transcriptomic effects in roots of soc1, agl24, xal2, and higher-order mutant backgrounds, with rescue by DNA-binding and partner-interaction mutant SOC1 alleles.

Hypothesis: SOC1's root-development role uses a subset of the same MADS partner and chromatin-recruitment mechanisms used at the shoot apex.

Type: genetics and functional genomics

Deep Research

Falcon

(SOC1-deep-research-falcon.md)

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πŸ“š Additional Documentation

Notes

(SOC1-notes.md)

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