APETALA2 (AP2; At4g36920; UniProt P47927) encodes a nuclear AP2/ERF-family DNA-binding transcription factor with two AP2/ERF DNA-binding domains and an EAR repression motif. AP2 is a canonical Arabidopsis A-class floral homeotic regulator that controls floral meristem and perianth organ identity, restricts floral homeotic gene expression, contributes to shoot meristem maintenance and floral-transition morphology, and regulates seed and ovule/seed-coat development. The best-supported molecular function is cis-regulatory DNA binding coupled to context-dependent transcriptional activation and repression; AP2 is post-transcriptionally restricted by miR172 and can repress targets through TOPLESS/HDA19-associated chromatin mechanisms. PANTHER places AP2 in family PTHR32467 (AP2-like ethylene-responsive transcription factor) and subfamily PTHR32467:SF142 (floral homeotic protein APETALA 2), consistent with conserved AP2/ERF transcription-factor function.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005667 transcription regulator complex | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: AP2 can act in transcriptional regulatory assemblies, including reported interactions with TOPLESS/HDA19 and MYBL2-containing regulatory complexes, so the broad component annotation is biologically plausible. However, the current IBA term is generic and does not describe AP2's core independently enabled activity, which is DNA-binding transcription factor activity. Reason: Retain as a non-core cellular-component context. AP2 participates in transcriptional regulatory complexes, but the annotation is broad and should not substitute for the core AP2/ERF DNA-binding transcription factor activity and nuclear cis-regulatory DNA-binding annotations. Supporting Evidence: file:ARATH/AP2/AP2-uniprot.txt Interacts with HDA19 and with TPL in an EAR-motif dependent manner file:ARATH/AP2/AP2-deep-research-falcon.md AP2 represses boundaries of multiple floral organ identity genes, including **AG, AP3, PI, SEP3**) by recruiting the co-repressor **TOPLESS (TPL)** and **HDA19** |
| GO:0006355 regulation of DNA-templated transcription | IBA GO_REF:0000033 | ACCEPT | Summary: This broad transcriptional-regulation process is consistent with AP2's conserved AP2/ERF transcription-factor family membership and direct AP2-specific literature showing target activation and repression. Reason: AP2's central function is regulation of gene expression through promoter binding. The generic BP term is broad but accurate because AP2 has both activating and repressing target outputs, making a single positive or negative regulation term insufficient for the whole protein. Supporting Evidence: PMID:7919989 APETALA2 (AP2) plays a central role in the establishment of the floral meristem, the specification of floral organ identity, and the regulation of floral homeotic gene expression in Arabidopsis. file:ARATH/AP2/AP2-deep-research-falcon.md AP2 is described as a multifunctional **transcription factor** controlling developmental transitions and organ identity, with experimentally supported **dual molecular roles** (activation and repression). |
| GO:0003677 DNA binding | IEA GO_REF:0000002 | MODIFY | Summary: The InterPro-derived DNA-binding annotation is directionally correct because AP2 contains AP2/ERF DNA-binding domains, but the term is too generic for a well-characterized sequence-specific transcription factor. Reason: Replace generic DNA binding with terms that capture AP2's actual molecular role: a DNA-binding transcription factor that binds transcriptional cis-regulatory regions. Proposed replacements: DNA-binding transcription factor activity transcription cis-regulatory region binding Supporting Evidence: PMID:7919989 We isolated the AP2 gene and found that it encodes a putative nuclear protein that is distinguished by an essential 68-amino acid repeated motif, the AP2 domain. file:ARATH/AP2/AP2-deep-research-falcon.md Molecular function: AP2-domain transcription factor; binds thousands of genomic loci; functions as activator and repressor depending on target and tissue. |
| GO:0003677 DNA binding | IEA GO_REF:0000117 | MODIFY | Summary: The ARBA DNA-binding annotation is correct at a high level but under-specific for AP2. The AP2 literature supports DNA-binding transcription factor activity and cis-regulatory region binding rather than undifferentiated DNA binding. Reason: Replace generic DNA binding with AP2's more informative transcription factor and promoter/cis-regulatory binding activities. Proposed replacements: DNA-binding transcription factor activity transcription cis-regulatory region binding Supporting Evidence: file:ARATH/AP2/AP2-uniprot.txt DNA_BIND 131..187 file:ARATH/AP2/AP2-uniprot.txt DNA_BIND 223..280 file:ARATH/AP2/AP2-deep-research-falcon.md AP2-domain transcription factor; binds thousands of genomic loci |
| GO:0003700 DNA-binding transcription factor activity | IEA GO_REF:0000002 | ACCEPT | Summary: AP2 contains two AP2/ERF DNA-binding domains and is a well-established transcription factor. Although this particular annotation is electronic, it is strongly corroborated by mutant, expression, direct-target, and family evidence. Reason: The term accurately represents AP2's core molecular activity. Supporting Evidence: PMID:15708976 Arabidopsis APETALA2 ( AP2 ) encodes a member of the AP2/EREBP (ethylene responsive element binding protein) class of transcription factors file:interpro/panther/PTHR32467/PTHR32467-entries.csv P47927,Floral homeotic protein APETALA 2,protein,3702,Arabidopsis thaliana,Arabidopsis thaliana (Mouse-ear cress),AP2,432,PTHR32467:SF142,FLORAL HOMEOTIC PROTEIN APETALA 2,True |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: AP2 is annotated by UniProt as nuclear and contains a predicted nuclear localization signal. Independent functional evidence for DNA binding and transcriptional regulation also places AP2's active site of function in the nucleus. Reason: Nucleus is the appropriate cellular location for AP2's DNA-binding transcription-factor activity. The direct cached literature mostly states this as predicted or functional inference rather than standalone imaging, but the localization is strongly supported by the protein's activity and UniProt annotation. Supporting Evidence: PMID:7919989 We isolated the AP2 gene and found that it encodes a putative nuclear protein file:ARATH/AP2/AP2-uniprot.txt SUBCELLULAR LOCATION: Nucleus |
| GO:0006355 regulation of DNA-templated transcription | IEA GO_REF:0000002 | ACCEPT | Summary: The InterPro-derived process annotation follows from AP2/ERF transcription-factor family membership and is supported by AP2-specific evidence for direct gene regulation. Reason: This broad BP term is correct for AP2 because AP2 directly regulates transcriptional targets in floral meristems, shoot meristems, and seed tissues. Supporting Evidence: PMID:7919989 the regulation of floral homeotic gene expression in Arabidopsis file:ARATH/AP2/AP2-deep-research-falcon.md AP2 can **directly induce** some genes (e.g., **AGL15**) while **directly repressing** others (e.g., **SOC1**). |
| GO:0000976 transcription cis-regulatory region binding | IPI PMID:25533953 An Arabidopsis gene regulatory network for secondary cell wa... | ACCEPT | Summary: The 2015 secondary cell wall network paper used yeast one-hybrid assays to map Arabidopsis transcription-factor binding to promoter fragments. The cached main text supports the assay framework but does not expose the AP2-specific supplementary row; nevertheless, AP2-specific ChIP and target evidence in the deep research independently supports the same term. Reason: The term is an appropriate molecular-function annotation for AP2. The original high-throughput source should be treated as supporting network evidence, while AP2-specific direct-target studies provide the stronger biological justification. Supporting Evidence: PMID:25533953 Promoter sequences were screened using an enhanced yeast one hybrid (Y1H) assay against 467 (89%) of root xylem-expressed transcription factors file:ARATH/AP2/AP2-deep-research-falcon.md Genome-wide direct targeting (Plant Cell 2010). AP2 ChIP-seq identified extensive binding: **2,275** bound regions |
| GO:0000976 transcription cis-regulatory region binding | IPI PMID:30356219 Transcriptional regulation of nitrogen-associated metabolism... | ACCEPT | Summary: The 2018 nitrogen-associated network paper is cached only as abstract text, so the AP2-specific interaction table cannot be verified here. The term is still correct for AP2 based on independent AP2-specific promoter-binding and ChIP-seq evidence summarized in the deep research. Reason: Accept the term, while noting the evidence limitation: the cached PMID:30356219 record does not contain the AP2-specific binding result. Independent direct AP2 evidence supports cis-regulatory region binding. Supporting Evidence: PMID:30356219 transcription factors that regulate the architecture of root and shoot systems file:ARATH/AP2/AP2-deep-research-falcon.md AP2 directly binds the SOC1 promoter and represses SOC1 in vegetative SAM |
| GO:0005634 nucleus | ISM GO_REF:0000122 | ACCEPT | Summary: The AtSubP prediction is consistent with UniProt's nuclear localization annotation, AP2's NLS, and the protein's DNA-binding transcription-factor function. Reason: Nucleus is the correct location for AP2's core transcriptional regulatory activity. Supporting Evidence: file:ARATH/AP2/AP2-uniprot.txt MOTIF 119..128 file:ARATH/AP2/AP2-uniprot.txt Nuclear localization signal |
| GO:0010093 specification of floral organ identity | IMP PMID:2535466 Genes directing flower development in Arabidopsis. | ACCEPT | Summary: The classic floral homeotic mutant analysis showed that apetala2-1 transforms first- and second-whorl organs and that wild-type AP2 acts at primordium initiation, supporting a role in specification of floral organ identity. Reason: This is a core AP2 developmental process annotation supported by loss-of-function floral-organ identity phenotypes. Supporting Evidence: PMID:2535466 Temperature shift experiments indicate that the wild-type AP2 gene product acts at the time of primordium initiation PMID:2535466 cells to determine their place in the developing flower and thus to differentiate appropriately |
| GO:0048481 plant ovule development | IGI PMID:22914576 BR signal influences Arabidopsis ovule and seed number throu... | KEEP AS NON CORE | Summary: The BR/BZR1 paper supports a genetic relationship between AP2 and ovule number/developmental gene expression, and independent AP2 seed papers also describe roles in ovule and seed-coat development. However, this annotation is a specific reproductive-development output rather than AP2's core molecular function, and the original cached paper is abstract-only. Reason: Keep as a supported non-core process. The evidence is consistent with AP2 influencing ovule development, but the main AP2 function remains nuclear transcriptional regulation of floral, meristem, and seed developmental programs. Supporting Evidence: PMID:22914576 the expression level of genes related to ovule development, including HLL, ANT, PMID:22914576 BZR1 and AP2 probably affect Arabidopsis ovule number determination PMID:15708976 development of the ovule and seed coat |
| GO:0010073 meristem maintenance | IMP PMID:16387832 APETALA2 regulates the stem cell niche in the Arabidopsis sh... | ACCEPT | Summary: AP2 was implicated in shoot meristem stem-cell niche maintenance through a dominant-negative allele that disrupts WUS and CLV3 expression and modifies the WUS-CLV3 feedback loop. Reason: The IMP annotation is supported by AP2 mutant phenotypes and molecular markers of the shoot meristem stem-cell niche. This process is part of the AP2 developmental regulatory program. Supporting Evidence: PMID:16387832 Expression of both WUSCHEL ( WUS ) and CLAVATA3 ( CLV3 ) genes, which regulate stem cell maintenance in the wild type, were disrupted PMID:16387832 AP2 functions in stem cell maintenance by modifying the WUS - CLV3 feedback loop |
| GO:0010093 specification of floral organ identity | IMP PMID:12359889 AP2 Gene Determines the Identity of Perianth Organs in Flowe... | ACCEPT | Summary: Three AP2 mutant alleles displayed homeotic perianth transformations, directly supporting AP2's role in specifying floral organ identity. Reason: This is one of the central AP2 functions and is supported by direct mutant phenotype analysis of perianth organ identity. Supporting Evidence: PMID:12359889 AP2 gene is required early in floral development to direct primordia of the first and second whorls to develop as perianth rather than as reproductive organs |
| GO:0048316 seed development | IMP PMID:15708974 Control of seed mass and seed yield by the floral homeotic g... | ACCEPT | Summary: Genetic analyses showed that AP2 affects seed size, seed weight, seed oil and protein accumulation, seed yield, and maternal/endosperm contributions to seed traits. Reason: The seed-development annotation is well supported by direct ap2 mutant and transgenic evidence. The term is broad but appropriate because AP2 affects several aspects of seed development rather than a single isolated seed phenotype. Supporting Evidence: PMID:15708974 AP2 also plays an important role in determining seed size, seed weight, and the accumulation of seed oil and protein. PMID:15708974 AP2 acts through the maternal sporophyte and endosperm genomes to control seed weight and seed yield. |
| GO:0048316 seed development | IMP PMID:15708976 Control of seed mass by APETALA2. | ACCEPT | Summary: Independent genetic analysis showed that loss-of-function ap2 mutations increase seed mass and that AP2 acts maternally, affecting embryo cell number, embryo cell size, and soluble sugar dynamics during seed development. Reason: The annotation is supported by direct loss-of-function and reciprocal-cross evidence for AP2 control of seed development and seed mass. Supporting Evidence: PMID:15708976 Reciprocal cross experiments showed that AP2 acts maternally to control seed mass. PMID:15708976 The maternal effect of AP2 on seed mass involves the regulation of both embryo cell number and cell size. |
| GO:0003700 DNA-binding transcription factor activity | TAS PMID:7919989 Control of Arabidopsis flower and seed development by the ho... | ACCEPT | Summary: The AP2 cloning paper identified AP2 as a putative nuclear regulatory protein with AP2 domains and connected this protein to floral and seed developmental regulation. Reason: DNA-binding transcription factor activity is the best supported core molecular function for AP2. Supporting Evidence: PMID:7919989 AP2 represents a new class of plant regulatory proteins PMID:7919989 the AP2 domain |
| GO:0003700 DNA-binding transcription factor activity | ISS PMID:11118137 Arabidopsis transcription factors: genome-wide comparative a... | ACCEPT | Summary: The ISS annotation is based on Arabidopsis transcription-factor family analysis. Although the cached paper is abstract-only and not AP2-specific in its abstract, the conclusion is consistent with AP2 family/domain and AP2-specific experimental evidence. Reason: Retain because AP2 is a well-established AP2/ERF DNA-binding transcription factor. The original source is broad comparative evidence, so stronger AP2-specific sources should be preferred for curation narratives. Supporting Evidence: PMID:11118137 Arabidopsis dedicates over 5% of its genome to code for more than 1500 file:interpro/panther/PTHR32467/PTHR32467-entries.csv P47927,Floral homeotic protein APETALA 2,protein,3702,Arabidopsis thaliana,Arabidopsis thaliana (Mouse-ear cress),AP2,432,PTHR32467:SF142,FLORAL HOMEOTIC PROTEIN APETALA 2,True |
| GO:0005634 nucleus | TAS PMID:7919989 Control of Arabidopsis flower and seed development by the ho... | ACCEPT | Summary: The original AP2 paper describes AP2 as a putative nuclear protein and identified the AP2 domain. This supports the nuclear annotation, though it is not a modern direct fluorescent-localization assay. Reason: Nucleus is consistent with AP2's predicted nuclear protein sequence, nuclear localization signal, and DNA-binding transcription-factor function. Supporting Evidence: PMID:7919989 it encodes a putative nuclear protein file:ARATH/AP2/AP2-uniprot.txt SUBCELLULAR LOCATION: Nucleus |
| GO:0006355 regulation of DNA-templated transcription | TAS PMID:7919989 Control of Arabidopsis flower and seed development by the ho... | ACCEPT | Summary: AP2 was described as regulating floral homeotic gene expression, and later direct-target studies establish AP2 as a transcriptional activator and repressor. Reason: The term accurately reflects AP2's central biological role in transcriptional regulation. Supporting Evidence: PMID:7919989 the regulation of floral homeotic gene expression in Arabidopsis file:ARATH/AP2/AP2-deep-research-falcon.md AP2 directly binds the SOC1 promoter and represses SOC1 transcription during vegetative development |
| GO:0030154 cell differentiation | TAS PMID:7919989 Control of Arabidopsis flower and seed development by the ho... | MODIFY | Summary: The original AP2 literature supports developmental cell fate and organ identity effects, but GO:0030154 is too generic for AP2 and obscures the specific floral homeotic process. Reason: Replace broad cell differentiation with AP2's specific, directly supported floral development and floral organ identity specification terms. Proposed replacements: specification of floral organ identity flower development Supporting Evidence: PMID:7919989 APETALA2 (AP2) plays a central role in the establishment of the floral meristem, the specification of floral organ identity, and the regulation of floral homeotic gene expression in Arabidopsis. PMID:2535466 cells to determine their place in the developing flower and thus to differentiate appropriately |
| GO:0005634 nucleus | ISS PMID:7919989 Control of Arabidopsis flower and seed development by the ho... | ACCEPT | Summary: The ISS nuclear annotation is consistent with the AP2 paper's putative nuclear protein description, UniProt's NLS and nuclear localization annotation, and AP2's DNA-binding transcription-factor function. Reason: Nucleus is the appropriate location for AP2 activity. Supporting Evidence: PMID:7919989 putative nuclear protein file:ARATH/AP2/AP2-uniprot.txt Nuclear localization signal |
| GO:0009908 flower development | TAS PMID:7919989 Control of Arabidopsis flower and seed development by the ho... | ACCEPT | Summary: AP2 is a floral homeotic regulator required for floral meristem identity, perianth organ identity, and normal flower development. Reason: Flower development is a broad but accurate AP2 biological-process annotation, supported by direct mutant and expression evidence. Supporting Evidence: PMID:7919989 in addition to its functions during flower development, AP2 activity is also required during seed development PMID:12359889 AP2 gene is required early in floral development |
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Download this section (compressed HTML)Q: Which AP2 direct target genes mediate seed mass and seed-coat metabolic phenotypes, and which effects are indirect consequences of altered floral or ovule development?
Q: What cofactors determine whether AP2 acts as a transcriptional activator or as a TOPLESS/HDA19-associated repressor at a given target locus?
Q: Are the AP2 cis-regulatory binding annotations from secondary cell wall and nitrogen-response network studies reproducible in AP2-expressing tissues?
Q: Which AP2-containing transcriptional assemblies are stable or direct enough to justify a more specific complex annotation than generic transcription regulator complex?
Experiment: Perform native-promoter AP2 CUT&RUN or ChIP-seq in floral meristems, shoot apices during floral transition, seed coat, and endosperm, paired with acute AP2 perturbation RNA-seq, to separate direct AP2 targets from downstream developmental effects.
Type: genomics
Experiment: Use AP2 affinity purification followed by mass spectrometry in flower and seed tissues to identify tissue-specific AP2 cofactors, including TOPLESS/HDA19 and MYBL2/MBW-related complexes.
Type: proteomics
Experiment: Edit AP2-bound cis-regulatory motifs at priority targets such as SOC1, AG, and MYBL2 and assay target expression plus meristem, floral organ, and seed phenotypes.
Type: genome editing
Experiment: Validate the AP2 high-throughput cis-regulatory binding calls from the secondary wall and nitrogen network studies using targeted EMSA, Y1H retesting, or ChIP-qPCR in relevant tissues.
Type: DNA binding assay
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