GL3

UniProt ID: Q9FN69
Organism: Arabidopsis thaliana
Review Status: DRAFT
Aliases:
BHLH1 EN31 MYC6 SST At5g41315
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Gene Description

GLABRA3 (GL3/AtbHLH1/MYC6) is an Arabidopsis basic helix-loop-helix transcription factor and bHLH component of MBW regulatory complexes. In the nucleus it partners with GL1/MYB23 or WER-family MYBs and TTG1 to activate epidermal cell-fate, trichome initiation, branching, and root non-hair programs; in other complexes it contributes to anthocyanin regulation. Generic protein-binding rows reflect real partner interactions but obscure the more informative bHLH transcription-factor and MBW-complex role.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0001708 cell fate specification
IMP
PMID:11063707
GL3 encodes a bHLH protein that regulates trichome developme... 		MODIFY
Summary: GL3 specifies epidermal/trichome fate in the MBW regulatory network.
Reason: Plant epidermal cell fate specification is the more precise supported process.
GO:0009867 jasmonic acid mediated signaling pathway
IMP
PMID:21551388
The Jasmonate-ZIM-domain proteins interact with the WD-Repea... 		KEEP AS NON CORE
Summary: Jasmonate regulators modulate GL3-containing MBW complexes during anthocyanin and trichome responses.
Reason: JA pathway involvement is a regulatory context rather than GL3 core molecular function.
GO:0010026 trichome differentiation
IMP
PMID:21551388
The Jasmonate-ZIM-domain proteins interact with the WD-Repea... 		ACCEPT
Summary: GL3 promotes trichome differentiation through the GL1/GL3/TTG1 MBW module.
Reason: Trichome differentiation is a core GL3 biological role.
Supporting Evidence:
file:ARATH/GL3/GL3-deep-research-falcon.md
GL3 activity can trigger trichome initiation within hours
GO:0010091 trichome branching
IMP
PMID:10572032
Genetic control of trichome branch number in Arabidopsis: th... 		ACCEPT
Summary: GL3 contributes to trichome branching and morphogenesis.
Reason: Trichome branching is an experimentally supported GL3 developmental output closely tied to its core trichome role. PMID:10572032 is retained as the GOA original reference for validation, while PMID:19247443 provides the GL3-specific support.
Supporting Evidence:
PMID:19247443
mutations in gl3 have a modest effect, primarily affecting branching, DNA endoreduplication and trichoblast size
file:ARATH/GL3/GL3-uniprot.txt
promotes trichome formation, branching and differentiation
GO:0031542 positive regulation of anthocyanin biosynthetic process
IMP
PMID:21551388
The Jasmonate-ZIM-domain proteins interact with the WD-Repea... 		KEEP AS NON CORE
Summary: GL3 can act in anthocyanin MBW complexes, but this is a context-specific output compared with its trichome/epidermal core role.
Reason: Anthocyanin regulation is supported but not the primary GL3 function in this review.
GO:0090628 plant epidermal cell fate specification
IMP
PMID:12917293
A network of redundant bHLH proteins functions in all TTG1-d... 		ACCEPT
Summary: GL3 and EGL3 specify epidermal cell fate with MYB and TTG1 partners.
Reason: Plant epidermal cell fate specification is a central GL3 biological process.
GO:0003677 DNA binding
IPI
PMID:19247443
A systems approach reveals regulatory circuitry for Arabidop... 		MODIFY
Summary: GL3 functions as a promoter-binding transcription factor; generic DNA binding is too broad.
Reason: Use transcription cis-regulatory region binding to capture promoter/regulatory DNA binding by the transcription factor.
GO:0000981 DNA-binding transcription factor activity, RNA polymerase II-specific
IC
PMID:19247443
A systems approach reveals regulatory circuitry for Arabidop... 		NEW
Summary: GL3 is a nuclear bHLH transcription factor that binds regulatory regions and activates RNA polymerase II transcriptional programs with GL1.
Reason: GOA contains only the broader DNA-binding transcription factor activity row, while direct Arabidopsis evidence supports the more specific RNA polymerase II transcription factor role.
Supporting Evidence:
PMID:19247443
Within this timeframe, GL3, in cooperation with GL1, binds to and activates expression of GLABRA2 (GL2)
GO:0003700 DNA-binding transcription factor activity
ISS
PMID:12679534
The basic helix-loop-helix transcription factor family in pl... 		MODIFY
Summary: GL3 is a bHLH transcription factor regulating gene expression programs.
Reason: GL3 is a transcription factor, but the RNA polymerase II-specific term is the more precise molecular function for this plant nuclear bHLH regulator.
GO:0005515 protein binding
IPI
PMID:11063707
GL3 encodes a bHLH protein that regulates trichome developme... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:12917293
A network of redundant bHLH proteins functions in all TTG1-d... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:14561633
A contradictory GLABRA3 allele helps define gene interaction... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:14627722
The bHLH genes GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3) ... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:15361138
Comprehensive identification of Arabidopsis thaliana MYB tra... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:15584952
Comparison of TRY and the closely related At1g01380 gene in ... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:15604688
ENHANCER of TRY and CPC 2 (ETC2) reveals redundancy in the r... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:17644729
Functional analysis of the epidermal-specific MYB genes CAPR... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:21551388
The Jasmonate-ZIM-domain proteins interact with the WD-Repea... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:24659329
Arabidopsis DELLA and JAZ proteins bind the WD-repeat/bHLH/M... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:32612234
Extensive signal integration by the phytohormone protein net... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0005515 protein binding
IPI
PMID:32844153
Quantitative insight into the combinatorial interactions wit... 		MARK AS OVER ANNOTATED
Summary: GL3 binds MYB, TTG1, bHLH, and inhibitory partners in MBW regulatory complexes, but generic protein binding obscures its bHLH transcription-factor role.
Reason: The informative molecular role is DNA-binding bHLH transcription factor activity and MBW complex participation; protein binding alone is too generic.
GO:0046983 protein dimerization activity
IEA
GO_REF:0000002 		ACCEPT
Summary: GL3 has a bHLH-domain-supported dimerization function relevant to transcriptional complex assembly.
Reason: Dimerization is a conserved and functionally relevant property of bHLH transcription factors.
GO:0006355 regulation of DNA-templated transcription
IEA
GO_REF:0000108 		MODIFY
Summary: GL3 regulates transcription as part of its core function, but the parent term is broad.
Reason: Regulation of transcription by RNA polymerase II is the better process context for a plant nuclear transcription factor.
GO:0009867 jasmonic acid mediated signaling pathway
IEA
GO_REF:0000117 		KEEP AS NON CORE
Summary: Jasmonate regulators modulate GL3-containing MBW complexes during anthocyanin and trichome responses.
Reason: JA pathway involvement is a regulatory context rather than GL3 core molecular function.
GO:0010026 trichome differentiation
IEA
GO_REF:0000117 		ACCEPT
Summary: GL3 promotes trichome differentiation through the GL1/GL3/TTG1 MBW module.
Reason: Trichome differentiation is a core GL3 biological role.
GO:0090628 plant epidermal cell fate specification
IEA
GO_REF:0000117 		ACCEPT
Summary: GL3 and EGL3 specify epidermal cell fate with MYB and TTG1 partners.
Reason: Plant epidermal cell fate specification is a central GL3 biological process.
GO:0005634 nucleus
IEA
GO_REF:0000044 		ACCEPT
Summary: The protein has nuclear localization consistent with its transcriptional regulatory role.
Reason: Nuclear localization is the expected functional compartment for this transcriptional regulator.
GO:0005634 nucleus
IEA
GO_REF:0000117 		ACCEPT
Summary: The protein has nuclear localization consistent with its transcriptional regulatory role.
Reason: Nuclear localization is the expected functional compartment for this transcriptional regulator.
GO:0005634 nucleus
ISM
GO_REF:0000122 		ACCEPT
Summary: The protein has nuclear localization consistent with its transcriptional regulatory role.
Reason: Nuclear localization is the expected functional compartment for this transcriptional regulator.
GO:0005634 nucleus
IDA
PMID:15590742
The bHLH genes GL3 and EGL3 participate in an intercellular ... 		ACCEPT
Summary: The protein has nuclear localization consistent with its transcriptional regulatory role.
Reason: Nuclear localization is the expected functional compartment for this transcriptional regulator.
GO:0005634 nucleus
IDA
PMID:21914815
Cell fate in the Arabidopsis root epidermis is determined by... 		ACCEPT
Summary: The protein has nuclear localization consistent with its transcriptional regulatory role.
Reason: Nuclear localization is the expected functional compartment for this transcriptional regulator.

Core Functions

Nuclear bHLH transcription factor in Arabidopsis MBW complexes. GL3 dimerizes through its bHLH domain and cooperates with GL1/MYB23/WER-family MYBs and TTG1 to regulate transcriptional programs for epidermal cell fate, trichome initiation, trichome branching, and root non-hair specification.

Molecular Function:
DNA-binding transcription factor activity, RNA polymerase II-specific
Directly Involved In:
trichome differentiation trichome branching plant epidermal cell fate specification
Cellular Locations:
nucleus
Supporting Evidence:
  • PMID:11063707
    GL3 encodes a bHLH protein that regulates trichome development in arabidopsis through interaction with GL1 and TTG1.
  • file:ARATH/GL3/GL3-deep-research-falcon.md
    GL3 activity can trigger trichome initiation within hours

References

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Suggested Questions for Experts

Q: Should GL3/TT8 family members use a shared bHLH transcription activator term when evidence supports activation rather than only generic DNA-binding TF activity?

Q: Can GOA distinguish GL3 trichome/root epidermis core functions from non-core anthocyanin-context functions?

Suggested Experiments

Experiment: Map GL3 genomic occupancy and rapid transcriptional targets in trichome initials and root epidermis using inducible GL3 nuclear entry combined with CUT&RUN and time-course RNA-seq.

Deep Research

Falcon

(GL3-deep-research-falcon.md)

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