GLABRA2 (GL2/ATHB10) is an Arabidopsis class IV HD-ZIP transcription factor that acts in the nucleus downstream of MBW epidermal fate complexes. GL2 binds cis-regulatory DNA through its homeodomain and regulates epidermal cell identity: it promotes non-root-hair/atrichoblast and trichome differentiation programs while repressing root-hair-promoting bHLH genes in non-hair cells. Seed oil, mucilage, anthocyanin, and other developmental effects are downstream outputs of this transcriptional regulator.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0010062 negative regulation of trichoblast fate specification | IMP PMID:8620852 The homeobox gene GLABRA2 is required for position-dependent... | ACCEPT | Summary: GL2 represses trichoblast/root hair fate in non-hair epidermal cells. Reason: Negative regulation of trichoblast fate is a core GL2 biological role. |
| GO:0090628 plant epidermal cell fate specification | IMP PMID:11844112 Entopically additive expression of GLABRA2 alters the freque... | ACCEPT | Summary: GL2 controls Arabidopsis epidermal cell fate in trichome and root epidermis contexts. Reason: Plant epidermal cell fate specification is a central GL2 process. |
| GO:0000976 transcription cis-regulatory region binding | IPI PMID:25533953 An Arabidopsis gene regulatory network for secondary cell wa... | KEEP AS NON CORE | Summary: GL2 binds regulatory promoter regions in gene regulatory network assays. Reason: Cis-regulatory binding is a valid molecular function of GL2, but this Y1H evidence is from a secondary-cell-wall/xylem network rather than the core GL2 epidermal fate context. Supporting Evidence: PMID:25533953 Promoter sequences were screened using an enhanced yeast one hybrid (Y1H) assay against 467 (89%) of root xylem-expressed transcription factors7. |
| GO:0000981 DNA-binding transcription factor activity, RNA polymerase II-specific | IEA GO_REF:0000002 | ACCEPT | Summary: GL2 functions as an RNA polymerase II transcription factor. Reason: The term captures the core transcription-factor role more specifically than generic DNA binding. Supporting Evidence: file:ARATH/GL2/GL2-deep-research-falcon.md GL2 recognizes an L1 box-like cis-element in target promoters |
| GO:0003677 DNA binding | IEA GO_REF:0000002 | MODIFY | Summary: GL2 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. Proposed replacements: transcription cis-regulatory region binding |
| GO:0003700 DNA-binding transcription factor activity | ISS PMID:11118137 Arabidopsis transcription factors: genome-wide comparative a... | MODIFY | Summary: GL2 is a DNA-binding transcription factor regulating gene expression programs. Reason: GL2 is a transcription factor, but the RNA polymerase II-specific term is the more precise molecular function for this plant nuclear HD-ZIP regulator. Proposed replacements: DNA-binding transcription factor activity, RNA polymerase II-specific |
| GO:0003700 DNA-binding transcription factor activity | ISS PMID:7926739 The GLABRA2 gene encodes a homeo domain protein required for... | MODIFY | Summary: GL2 is a DNA-binding transcription factor regulating gene expression programs. Reason: GL2 is a transcription factor, but the RNA polymerase II-specific term is the more precise molecular function for this plant nuclear HD-ZIP regulator. Proposed replacements: DNA-binding transcription factor activity, RNA polymerase II-specific |
| GO:0008289 lipid binding | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: The START-domain InterPro mapping suggests possible lipid binding, but GL2-specific ligand binding is not established as a core function. Reason: Without direct GL2 ligand evidence, lipid binding is an over-projected domain annotation relative to the supported transcription-factor role. |
| GO:0043565 sequence-specific DNA binding | IPI PMID:26486447 GLABRA2 Directly Suppresses Basic Helix-Loop-Helix Transcrip... | MODIFY | Summary: GL2 binds sequence-specific L1 box-like elements in target promoters. Reason: Transcription cis-regulatory region binding is the current more precise term for promoter DNA binding by GL2. Proposed replacements: transcription cis-regulatory region binding Supporting Evidence: PMID:26486447 GLABRA2 directly suppresses basic helix-loop-helix transcription factor genes with diverse functions in root hair development. |
| GO:0006355 regulation of DNA-templated transcription | IEA GO_REF:0000002 | MODIFY | Summary: GL2 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. Proposed replacements: regulation of transcription by RNA polymerase II |
| GO:0006357 regulation of transcription by RNA polymerase II | IEA GO_REF:0000108 | ACCEPT | Summary: GL2 regulates RNA polymerase II transcriptional programs. Reason: RNA polymerase II transcriptional regulation is a core biological process for this nuclear transcription factor. |
| GO:0030154 cell differentiation | IEA GO_REF:0000117 | MODIFY | Summary: GL2 affects epidermal cell differentiation, but the annotation is too broad. Reason: Plant epidermal cell fate specification is the more informative supported process. Proposed replacements: plant epidermal cell fate specification |
| 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 | 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:16581911 Transcriptional and posttranscriptional regulation of transc... | 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 | EXP PMID:28526410 Adaptor proteins GIR1 and GIR2. I. Interaction with the repr... | 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. Supporting Evidence: PMID:28526410 interacting proteins accumulated predominantly in the cell nucleus. |
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Download this section (compressed HTML)Q: Should GL2 lipid-binding annotations from START-domain InterPro mapping remain in GOA without direct Arabidopsis ligand evidence?
Q: Can GL2 target-gene annotations be split between root epidermis, trichome, seed coat mucilage, and secondary-wall contexts?
Experiment: Use GL2 DNA-binding-domain and START-domain variants in complementation assays with ChIP-qPCR/RNA-seq to distinguish direct transcriptional targets from domain-dependent protein stability effects.
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