GO Term	Evidence	Action	Reason
GO:0019005 SCF ubiquitin ligase complex	IDA PMID:10398681 Identification of an SCF ubiquitin-ligase complex required f...	ACCEPT	Summary: TIR1 is a component of SCF(TIR1) ubiquitin ligase complexes. Reason: The SCF complex context is central to TIR1's auxin receptor/substrate-recognition function.
GO:0000151 ubiquitin ligase complex	IDA PMID:10398681 Identification of an SCF ubiquitin-ligase complex required f...	MODIFY	Summary: TIR1 is in a ubiquitin ligase complex, but the SCF-specific term is more precise. Reason: SCF ubiquitin ligase complex better captures the TIR1-containing complex. Proposed replacements: SCF ubiquitin ligase complex
GO:0010011 auxin binding	IDA PMID:17410169 Mechanism of auxin perception by the TIR1 ubiquitin ligase.	ACCEPT	Summary: Structural work shows auxin bound in the TIR1 receptor pocket. Reason: Auxin binding is a direct molecular property of TIR1.
GO:0010011 auxin binding	IDA PMID:18391211 Small-molecule agonists and antagonists of F-box protein-sub...	ACCEPT	Summary: Auxin agonist/antagonist studies support ligand binding by TIR1. Reason: Auxin binding is a direct molecular property of TIR1. Supporting Evidence: PMID:18391211 their mode of action in binding to TIR1 is confirmed by x-ray crystallographic analysis
GO:0038198 auxin receptor activity	IDA PMID:15917797 The F-box protein TIR1 is an auxin receptor.	ACCEPT	Summary: TIR1 is an auxin receptor that mediates Aux/IAA degradation and auxin-regulated transcription. Reason: Auxin receptor activity is the core molecular function of TIR1. Supporting Evidence: file:ARATH/TIR1/TIR1-deep-research-falcon.md
GO:0000822 inositol hexakisphosphate binding	IDA PMID:17410169 Mechanism of auxin perception by the TIR1 ubiquitin ligase.	KEEP AS NON CORE	Summary: The TIR1 structure contains an inositol hexakisphosphate cofactor. Reason: This is a supported cofactor-binding feature of the TIR1 receptor pocket, but the core molecular roles are auxin receptor and substrate-adaptor activity.
GO:0004842 ubiquitin-protein transferase activity	IC PMID:10398681 Identification of an SCF ubiquitin-ligase complex required f...	MODIFY	Summary: TIR1 contributes to SCF E3 ligase function as an F-box substrate receptor, but it is not the catalytic RING subunit. Reason: The term overstates TIR1's independent catalytic role; TIR1 is better represented as the auxin-dependent substrate adaptor of SCF(TIR1). Proposed replacements: ubiquitin-like ligase-substrate adaptor activity
GO:0009734 auxin-activated signaling pathway	IMP PMID:18391211 Small-molecule agonists and antagonists of F-box protein-sub...	ACCEPT	Summary: TIR1 mediates auxin-activated signaling through auxin-dependent Aux/IAA recruitment and degradation. Reason: This is the central biological process controlled by TIR1. Supporting Evidence: PMID:18391211 Auxin binding enhances the interaction between TIR1 and its substrates, the Aux/IAA repressors
GO:0016036 cellular response to phosphate starvation	IEP PMID:19106375 Phosphate availability alters lateral root development in Ar...	KEEP AS NON CORE	Summary: TIR1-dependent auxin sensitivity affects root responses to phosphate availability. Reason: Phosphate starvation response is a physiological output of auxin signaling.
GO:0010311 lateral root formation	IMP PMID:9436980 The TIR1 protein of Arabidopsis functions in auxin response ...	KEEP AS NON CORE	Summary: tir1 mutants affect lateral root formation. Reason: Lateral root formation is a downstream developmental output of auxin signaling.
GO:0010152 pollen maturation	IGI PMID:18628351 Auxin regulates Arabidopsis anther dehiscence, pollen matura...	KEEP AS NON CORE	Summary: Auxin signaling through TIR1/AFB proteins contributes to pollen maturation. Reason: Pollen maturation is a downstream reproductive output.
GO:0009733 response to auxin	IMP PMID:26236497 Untethering the TIR1 auxin receptor from the SCF complex inc...	KEEP AS NON CORE	Summary: Altering TIR1 stability and SCF association changes auxin response. Reason: The response term is correct but less mechanistic than auxin receptor activity and auxin-activated signaling.
GO:0009733 response to auxin	IMP PMID:9436980 The TIR1 protein of Arabidopsis functions in auxin response ...	KEEP AS NON CORE	Summary: tir1 mutants are deficient in auxin response phenotypes. Reason: The response term is correct but less mechanistic than auxin receptor activity and auxin-activated signaling.
GO:0048443 stamen development	IGI PMID:18628351 Auxin regulates Arabidopsis anther dehiscence, pollen matura...	KEEP AS NON CORE	Summary: Auxin signaling through TIR1/AFB proteins contributes to stamen development. Reason: Stamen development is a downstream reproductive output.
GO:0006511 ubiquitin-dependent protein catabolic process	TAS PMID:11019805 Protein degradation in signaling.	MODIFY	Summary: TIR1 participates in ubiquitin-dependent degradation, but the SCF-dependent term is more precise. Reason: TIR1 functions in SCF-dependent Aux/IAA degradation rather than generic ubiquitin-dependent catabolism. Proposed replacements: SCF-dependent proteasomal ubiquitin-dependent protein catabolic process
GO:0031146 SCF-dependent proteasomal ubiquitin-dependent protein catabolic process	IBA GO_REF:0000033	ACCEPT	Summary: TIR1 family context supports SCF-dependent proteasomal degradation of Aux/IAA repressors. Reason: This is the core mechanistic process downstream of auxin-bound TIR1.

Deep Research

Falcon

(TIR1-deep-research-falcon.md)

Research Report: Arabidopsis thaliana TIR1 (UniProt Q570C0; At3g62980) Falcon Edison Scientific Literature 44 citations 2026-05-07T08:55:37.563326

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Research Report: Arabidopsis thaliana TIR1 (UniProt Q570C0; At3g62980)

Scope and identity verification

The research target is TRANSPORT INHIBITOR RESPONSE 1 (TIR1) from Arabidopsis thaliana, corresponding to At3g62980 and functioning as a founding member of the plant TIR1/AFB auxin receptor family. Primary biochemical evidence shows that Arabidopsis TIR1 is an F-box protein within an SCF E3 ubiquitin ligase complex (SCF^TIR1) that binds auxin and mediates auxin-dependent recruitment of Aux/IAA transcriptional repressors for ubiquitination and 26S proteasome degradation, matching the UniProt domain description (F-box + LRRs) for UniProt Q570C0. (dharmasiri2005thefboxprotein pages 2-3, dharmasiri2005thefboxprotein pages 3-5, dharmasiri2005thefboxprotein pages 1-2)

1) Key concepts and definitions (current understanding)

Canonical nuclear auxin signaling and the “molecular glue” model

In the canonical (“nuclear”) auxin pathway, auxin perception is executed by TIR1/AFB receptors that are F-box subunits of SCF E3 ubiquitin ligases. Auxin acts as a molecular glue that stabilizes a ternary co-receptor complex between the TIR1/AFB LRR pocket and the domain II degron of Aux/IAA repressors (core motif often summarized as GWPP[VIL]), triggering Aux/IAA ubiquitination and proteasomal degradation. This degradation releases ARF transcription factors from repression (often via TOPLESS co-repressors), enabling auxin-responsive gene expression (including negative feedback via Aux/IAA induction). (roij2024proteindegradationin pages 3-4, vanneste2025mechanismsofauxin pages 10-13, ang2023saveyourtirs pages 2-3)

SCF^TIR1 complex definition and components

TIR1 is the substrate-recognition F-box subunit of SCF^TIR1, assembling with ASK1 (SKP1-like), CUL1, and RBX1 to recruit an E2 enzyme and catalyze ubiquitin transfer to substrates. SCF assembly and activity are dynamically regulated by RUB/NEDD8 conjugation cycles and modulators including the COP9 signalosome and CAND1, aligning auxin perception with broader ubiquitin–proteasome system (UPS) control. (dharmasiri2005thefboxprotein pages 2-3, roij2024proteindegradationin pages 2-3, roij2024proteindegradationin pages 3-4)

Visual summary (recommended reference): a schematic that integrates the UPS cascade, domain architectures (TIR1/AFB, Aux/IAA, ARF), and the canonical auxin-triggered degradation mechanism is presented in Figure 2 of de Roij et al., The Plant Cell (Apr 2024). (roij2024proteindegradationin media 293a5f1a)

2) Molecular function: domains, ligand/substrate specificity, partners, localization

Domain architecture and structural determinants

TIR1 is an F-box/LRR protein with an N-terminal F-box required for SCF assembly and a C-terminal LRR solenoid (horseshoe-like) that forms the auxin-binding pocket and interface for Aux/IAA degron recognition. Depending on annotation/structural treatment, the LRR count is described as ~16–18 repeats. (dharmasiri2005thefboxprotein pages 3-5, chaisupa2024understandingandengineering pages 134-138, yu2012analysisofthe pages 37-43)

Mutational studies demonstrate that specific residues within the LRR region tune co-receptor affinity: for example, D170E and M473L substitutions increase interaction with Aux/IAA degrons, accelerate Aux/IAA turnover, and cause auxin-hypersensitive phenotypes, supporting the view that TIR1’s primary role is ligand-regulated substrate recognition rather than enzymatic catalysis. (yu2012analysisofthe pages 98-110, yu2012analysisofthe pages 132-146)

Primary substrates

The key physiological substrates of SCF^TIR1 are Aux/IAA transcriptional repressors, whose degradation is determined by a conserved domain II auxin degron (commonly summarized as GWPPV in Arabidopsis examples). (dharmasiri2005thefboxprotein pages 1-2, shengjuan2024effectofmodulation pages 33-37, roij2024proteindegradationin pages 3-4)

Ligand specificity

TIR1 binds the natural auxin indole-3-acetic acid (IAA) and can be engaged by certain synthetic auxins, with ligand selectivity varying across receptor clades (TIR1, AFB2, AFB5). A 2023 quantitative receptor–ligand selectivity study using SPR (AtTIR1/AFB-ASK1 complexes) measured equilibrium affinities for IAA and multiple auxin herbicides, showing IAA Kd = 7.9 µM for AtTIR1 (and 12.6 µM for AtAFB2, 33 µM for AtAFB5). (prusinska2023thedifferentialbinding pages 4-5)

Foundational biochemical assays (2005) also directly measured auxin binding to the receptor complex, reporting an apparent Kd ~84 nM for IAA in SCF^TIR1-associated binding assays and competition IC50 estimates for IAA and synthetic auxins/herbicides. These measurements were done using extracts and recombinant components and should be interpreted in that experimental context (including the caveat of endogenous auxin in crude extracts). (dharmasiri2005thefboxprotein pages 2-3)

Protein–protein partners

Core complex partners are ASK1, CUL1, RBX1 (SCF assembly), and the direct auxin-dependent binding partners include Aux/IAAs such as IAA7 (used frequently as a degron substrate in biochemical assays). (dharmasiri2005thefboxprotein pages 2-3, roij2024proteindegradationin pages 2-3)

Subcellular localization (current evidence)

TIR1’s best-supported physiological role is in the nucleus, consistent with canonical transcriptional auxin signaling. Comparative analyses of the family highlight that AFB1 is unusually cytoplasm-enriched and specialized for rapid non-transcriptional auxin responses, whereas TIR1 is primarily nuclear, underscoring functional partitioning within the receptor family rather than re-defining TIR1’s main site of action. (dubey2023theafb1auxin pages 4-5, dubey2023theafb1auxin pages 8-11)

3) Recent developments (prioritizing 2023–2024)

Expansion beyond the “canonical-only” model: non-canonical branches and receptor diversification

A 2023 Tansley Insight emphasized that the canonical TIR1/AFB-Aux/IAA degradation pathway cannot fully explain very rapid auxin responses and highlighted evidence for a parallel, non-transcriptional branch of TIR1/AFB-related signaling and interplay with TMK-mediated cell-surface pathways affecting rapid growth responses and apoplastic pH control. (ang2023saveyourtirs pages 1-2, ang2023saveyourtirs pages 2-3)

A 2023 primary study demonstrated that AFB1 controls a rapid, cytoplasmic auxin response involving CNGC14-dependent Ca2+ transients, and that AFB1’s N-terminus determines cytoplasmic enrichment and rapid-response function; this work reframes the receptor family as functionally diversified, with TIR1 remaining central to canonical nuclear outputs while other family members contribute to distinct fast responses. (dubey2023theafb1auxin pages 8-11, dubey2023theafb1auxin pages 4-5)

Expert synthesis (2024): auxin response as a broader proteolysis network

A 2024 Plant Cell review situates SCF^TIR1/AFB within a broader landscape of proteolysis in auxin response, integrating classical genetics (AXR genes, TIR1 discovery) and mechanistic SCF regulation, while highlighting emerging complexity in how proteolytic systems intersect with auxin signaling networks. (roij2024proteindegradationin pages 2-3, roij2024proteindegradationin pages 3-4)

4) Current applications and real-world implementations

(A) Agriculture: auxin herbicides and receptor-selective pharmacology

Auxinic herbicides are anticipated to act initially via binding to TIR1-family receptors, and receptor selectivity helps explain differential herbicidal spectra. In a quantitative 2023 study, purified receptors were tested by SPR and paired with whole-plant assays. The data show strong selectivity of 6-arylpicolinate herbicides toward AFB5 (e.g., florpyrauxifen Kd 2.7 µM at AFB5 vs 62 µM at TIR1; halauxifen Kd 2.4 µM at AFB5 vs 128 µM at TIR1), whereas TIR1 binds IAA most strongly among tested receptors. (prusinska2023thedifferentialbinding pages 4-5)

Whole-plant dose–response assays further demonstrated functional consequences of receptor specificity: in afb5-1, growth-reduction metrics (GR50) shift to higher herbicide doses (e.g., halauxifen GR50 0.08 g ai ha−1 (WT) vs 0.6 (afb5-1); florpyrauxifen 0.1 vs 1), illustrating how receptor–ligand interactions translate into resistance and efficacy phenotypes. (prusinska2023thedifferentialbinding pages 4-5)

(B) Biotechnology: auxin-inducible degron (AID/AID2) systems

TIR1 biology has been transplanted into non-plant eukaryotes as the auxin-inducible degron (AID) platform, where ectopic TIR1 (often rice OsTIR1 for vertebrate compatibility) recruits host SCF machinery to degrade AID-tagged targets upon auxin addition. A 2024 review summarizes major AID improvements addressing auxin toxicity and basal degradation, including bump-and-hole strategies (e.g., AID2, ssAID) that pair engineered TIR1 variants with synthetic auxins. (ogawa2024targetedproteindegradation pages 2-4)

C. elegans (protocolized implementation, 2024): A 2024 STAR Protocol details practical deployment of tissue-specific TIR1 strains and CRISPR-based AID tagging to enable conditional protein depletion in vivo. (sharma2024protocolforauxininducible pages 1-3)

Mouse (AID2, 2024): A 2024 study established knock-in mouse lines expressing TIR1(F74G) (AID2) and demonstrated depletion of AID-tagged proteins within hours after intraperitoneal delivery of 5-Ph-IAA, with a knockout-like phenotype for an endogenously tagged factor within ~20 h. (makino‐itou2024establishmentandcharacterization pages 1-2)

Parasite systems (2024): An AID system was implemented in Babesia duncani via stable expression of OsTIR1; auxin treatment triggered measurable, dose-dependent degradation of an AID-eGFP reporter, enabling conditional knockdown in a non-model pathogen context. (chen2024establishmentofthe pages 1-2)

5) Relevant statistics and quantitative data (selected)

Auxin binding and ligand competition (TIR1 receptor biochemistry)

In the foundational receptor study, auxin binding to the SCF^TIR1 complex yielded an apparent IAA Kd ~84 nM (Scatchard analysis) and competition experiments reported IC50 ~0.12 mM (IAA), 1.3 mM (1-NAA), 1.4 mM (2,4-D) under the reported assay conditions. (dharmasiri2005thefboxprotein pages 2-3)

Receptor–herbicide selectivity (2023 SPR + plant assays)

SPR-derived Kd values (µM) for key ligands in Arabidopsis receptor clades include: IAA 7.9 (TIR1), 12.6 (AFB2), 33 (AFB5); 2,4-D 229 (TIR1), 392 (AFB2), 152 (AFB5); florpyrauxifen 62 (TIR1), 105 (AFB2), 2.7 (AFB5); halauxifen 128 (TIR1), 333 (AFB2), 2.4 (AFB5). (prusinska2023thedifferentialbinding pages 4-5)

AID/AID2 performance metrics (cross-species engineering)

Engineered AID systems typically achieve substantial depletion of most targets in ~15 minutes to 3 hours (depending on expression level, target, and ligand), with recovery time inversely related to auxin concentration. (vicencio2025engineeringtheauxininducible pages 1-3)

In Babesia duncani, auxin-mediated depletion of an AID-eGFP reporter at 500 µM IAA produced a 61.3% reduction by Western blot grayscale analysis and 77.5% decrease in fluorescence intensity; increasing auxin concentration to 2 mM accelerated and increased degradation. (chen2024establishmentofthe pages 1-2)

Expert synthesis and interpretation

Collectively, the strongest evidence supports a primary functional annotation for TIR1 as a nuclear F-box/LRR auxin receptor whose defining biochemical role is ligand-dependent substrate recruitment of Aux/IAA repressors to the SCF^TIR1 ubiquitin ligase, controlling transcriptional auxin responses via regulated proteolysis. (dharmasiri2005thefboxprotein pages 2-3, roij2024proteindegradationin pages 3-4)

Recent (2023–2024) literature increasingly frames auxin signaling as a network comprising canonical nuclear proteolysis and additional rapid/non-canonical branches, with receptor family diversification (notably AFB1) providing mechanistic routes to rapid responses; this broadens auxin biology without changing the core functional assignment of TIR1 as the canonical receptor driving Aux/IAA turnover. (ang2023saveyourtirs pages 1-2, dubey2023theafb1auxin pages 8-11)

Summary table (evidence map)

The table below compiles key annotation facts, recent developments, applications, and quantitative statistics in a compact format.

Aspect	Key details	Best supporting citations
Verified identity	Arabidopsis thaliana TIR1 / TRANSPORT INHIBITOR RESPONSE 1 corresponds to At3g62980, UniProt Q570C0 and is the canonical F-box/LRR auxin receptor in the SCF^TIR1 E3 ubiquitin ligase; this matches the UniProt domain architecture and excludes confusion with unrelated TIR1 symbols from other organisms.	(dharmasiri2005thefboxprotein pages 2-3, dharmasiri2005thefboxprotein pages 3-5, roij2024proteindegradationin pages 2-3)
Molecular function	TIR1 is the substrate-recognition F-box subunit of an SCF ubiquitin ligase that also acts as an auxin receptor/co-receptor. Auxin binding promotes TIR1 interaction with Aux/IAA repressors, triggering their ubiquitination and 26S proteasome degradation.	(dharmasiri2005thefboxprotein pages 2-3, dharmasiri2005thefboxprotein pages 1-2, roij2024proteindegradationin pages 2-3)
Core biochemical role	In canonical nuclear auxin signaling, auxin acts as a molecular glue that stabilizes the TIR1/AFB–Aux/IAA degron complex; Aux/IAA destruction releases ARF transcription factors to activate auxin-responsive genes.	(ang2023saveyourtirs pages 2-3, roij2024proteindegradationin pages 3-4)
Complex components / partners	TIR1 functions in SCF^TIR1 with ASK1 (SKP1 homolog), CUL1, and RBX1; direct functional partners include Aux/IAA proteins such as IAA7. SCF assembly/activity is tuned by RUB/NEDD8, AXR1, COP9 signalosome, and CAND1.	(dharmasiri2005thefboxprotein pages 2-3, roij2024proteindegradationin pages 2-3, yu2012analysisofthe pages 37-43, roij2024proteindegradationin pages 3-4)
Key domains / structure	Protein architecture includes an N-terminal F-box required for SCF assembly and a C-terminal leucine-rich repeat (LRR) solenoid/horseshoe domain that forms the auxin/Aux-IAA binding pocket; reports describe 16–18 LRRs depending on annotation/structural treatment.	(yu2012analysisofthe pages 37-43, dharmasiri2005thefboxprotein pages 3-5, chaisupa2024understandingandengineering pages 134-138)
Substrates	Primary substrates are Aux/IAA transcriptional repressors bearing domain II / degron motifs; the degron core is reported as GWPPV or within a 13-aa core motif GWPP[VIL].	(dharmasiri2005thefboxprotein pages 1-2, roij2024proteindegradationin pages 3-4, shengjuan2024effectofmodulation pages 33-37)
Ligand specificity	Natural IAA is the best-characterized ligand. TIR1 also recognizes synthetic auxins/herbicides with receptor-selective differences across the TIR1/AFB family; TIR1 generally binds IAA more strongly than AFB5, whereas AFB5 shows strong preference for 6-arylpicolinate herbicides such as halauxifen/florpyrauxifen.	(prusinska2023thedifferentialbinding pages 7-10, prusinska2023thedifferentialbinding pages 4-5)
Quantitative binding data	Foundational auxin-binding assays with Arabidopsis extracts/recombinant TIR1 reported an apparent IAA Kd ~84 nM for SCF^TIR1-associated binding; competition assays gave IC50 ~0.12 mM (IAA), 1.3 mM (1-NAA), 1.4 mM (2,4-D).	(dharmasiri2005thefboxprotein pages 2-3)
Recent receptor-selectivity data (2023)	SPR with purified receptor–ASK1 complexes: IAA Kd = 7.9 µM (TIR1), 12.6 µM (AFB2), 33 µM (AFB5). 2,4-D Kd = 229 µM (TIR1), 392 µM (AFB2), 152 µM (AFB5). Florpyrauxifen Kd = 62 µM (TIR1), 105 µM (AFB2), 2.7 µM (AFB5); Halauxifen Kd = 128 µM (TIR1), 333 µM (AFB2), 2.4 µM (AFB5).	(prusinska2023thedifferentialbinding pages 4-5)
Structural/functional determinants	Mutations D170E and M473L in the TIR1 LRR region increase Aux/IAA degron affinity, accelerate Aux/IAA degradation, and confer auxin hypersensitivity; the F-box/H1 region is also important for ASK1/CUL1 engagement and receptor stability.	(yu2012analysisofthe pages 98-110, yu2012analysisofthe pages 132-146)
Cellular localization	Canonical TIR1 function is predominantly nuclear, consistent with its role in transcriptional auxin signaling. Comparison with AFB1 indicates TIR1 is primarily nuclear, whereas AFB1 is more cytoplasmic and specialized for rapid non-transcriptional responses.	(dubey2023theafb1auxin pages 4-5, dubey2023theafb1auxin pages 8-11)
Pathway role	TIR1 is central to the canonical nuclear auxin pathway: low auxin allows Aux/IAA-mediated ARF repression; elevated auxin promotes SCF^TIR1/AFB-dependent Aux/IAA turnover, derepressing ARFs and inducing genes such as Aux/IAAs and SAURs.	(vanneste2025mechanismsofauxin pages 10-13, ang2023saveyourtirs pages 2-3, roij2024proteindegradationin pages 3-4)
Biological processes clarified by mechanism	Through precise control of Aux/IAA stability, TIR1 contributes to growth, root architecture, gravitropism, and many developmental outputs; mechanistically, these derive from quantitative tuning of ARF transcriptional activity rather than TIR1 acting as an enzyme or transporter.	(vanneste2025mechanismsofauxin pages 10-13, roij2024proteindegradationin pages 3-4)
Regulation / PTMs	TIR1 is regulated post-transcriptionally and post-translationally: miR393 targets TIR1/AFB transcripts; S-nitrosylation at C140 enhances TIR1–Aux/IAA interaction; receptor stability can involve SGT1b/HSP90; SCF activity depends on CUL1 rubylation/derubylation cycles.	(yu2012analysisofthe pages 132-146, yu2012analysisofthe pages 37-43, roij2024proteindegradationin pages 3-4)
Recent developments 2023–2024	The field now recognizes non-canonical auxin signaling alongside canonical TIR1 action. 2023 work emphasized rapid, non-transcriptional branches and receptor specialization (especially AFB1), while reviews highlighted possible adenylate cyclase/cAMP-related activity and regulated receptor trafficking as emerging concepts relevant to TIR1/AFB biology.	(ang2023saveyourtirs pages 4-5, ang2023saveyourtirs pages 2-3, ang2023saveyourtirs pages 1-2)
Evolution / family context	Arabidopsis has 6 TIR1/AFB receptors and 29 Aux/IAA proteins, enabling many receptor–repressor combinations with distinct affinities and tissue outputs; TIR1 is the founding member of this receptor family.	(yu2012analysisofthe pages 37-43, su2023differentevolutionarypatterns pages 1-2, shengjuan2024effectofmodulation pages 33-37)
Herbicide relevance / real-world application	TIR1-family receptor pharmacology underlies the action of auxinic herbicides. In Arabidopsis, the afb5-1 mutant shows shifted herbicide sensitivity, e.g. halauxifen GR50 0.08 g ai ha−1 (WT) vs 0.6 (afb5-1) and florpyrauxifen 0.1 vs 1, illustrating receptor-selective agronomic effects.	(prusinska2023thedifferentialbinding pages 7-10, prusinska2023thedifferentialbinding pages 4-5)
Biotechnology application	TIR1 biology has been repurposed in the auxin-inducible degron (AID/AID2) platform for rapid, reversible protein depletion in non-plant systems. Engineered TIR1 variants plus auxin analogs enable conditional degradation in yeast, worms, mice, and parasites.	(ogawa2024targetedproteindegradation pages 2-4, makino‐itou2024establishmentandcharacterization pages 1-2, chen2024establishmentofthe pages 1-2, sharma2024protocolforauxininducible pages 1-3)
AID/AID2 quantitative performance	Recent implementations report: most target depletion in ~15 min to 3 h in vivo for optimized systems; TIR1(F79G)/AID2 responds to 5-Ph-IAA at ~670-fold lower concentration than IAA; mouse AID2 gives depletion within a few to several hours and a knockout-like phenotype for DCP2 within 20 h; in Babesia duncani, 500 µM IAA reduced AID-eGFP by 61.3% (WB) and 77.5% (fluorescence).	(vicencio2025engineeringtheauxininducible pages 1-3, makino‐itou2024establishmentandcharacterization pages 1-2, chen2024establishmentofthe pages 1-2)
Useful visual source	A current schematic summarizing the UPS cascade, TIR1/AFB domain organization, canonical Aux/IAA degradation pathway, and SCF^TIR1/AFB complex regulation is available as Figure 2 in the 2024 Plant Cell review.	(roij2024proteindegradationin media 293a5f1a)

Table: This table summarizes the core functional annotation of Arabidopsis thaliana TIR1, including molecular role, partners, domains, localization, pathway context, recent developments, and quantitative data. It is designed as a compact evidence map for report writing and citation tracing.

Key referenced sources (with URLs and publication dates)

Dharmasiri N, Dharmasiri S, Estelle M. “The F-box protein TIR1 is an auxin receptor.” Nature (May 2005). https://doi.org/10.1038/nature03543 (dharmasiri2005thefboxprotein pages 2-3)
Ang ACH, Østergaard L. “Save your TIRs – more to auxin than meets the eye.” New Phytologist (Feb 2023). https://doi.org/10.1111/nph.18783 (ang2023saveyourtirs pages 1-2)
Dubey SM et al. “The AFB1 auxin receptor controls the cytoplasmic auxin response pathway in Arabidopsis thaliana.” Molecular Plant (Jul 2023). https://doi.org/10.1016/j.molp.2023.06.008 (dubey2023theafb1auxin pages 8-11)
de Roij M, Borst JW, Weijers D. “Protein degradation in auxin response.” The Plant Cell (Apr 2024). https://doi.org/10.1093/plcell/koae125 (roij2024proteindegradationin pages 3-4)
Prusinska J et al. “The differential binding and biological efficacy of auxin herbicides.” Pest Management Science (Dec 2023). https://doi.org/10.1002/ps.7294 (prusinska2023thedifferentialbinding pages 4-5)
Ogawa Y et al. “Targeted Protein Degradation Systems: Controlling Protein Stability Using E3 Ubiquitin Ligases in Eukaryotic Species.” Cells (Jan 2024). https://doi.org/10.3390/cells13020175 (ogawa2024targetedproteindegradation pages 2-4)
Sharma N et al. “Protocol for auxin-inducible protein degradation in C. elegans…” STAR Protocols (Sep 2024). https://doi.org/10.1016/j.xpro.2024.103133 (sharma2024protocolforauxininducible pages 1-3)
Makino-Itou H et al. “Establishment and characterization of mouse lines… (AID2).” Development, Growth & Differentiation (Sep 2024). https://doi.org/10.1111/dgd.12942 (makino‐itou2024establishmentandcharacterization pages 1-2)
Chen B et al. “Establishment of the auxin inducible degron system for Babesia duncani…” Parasites & Vectors (Oct 2024). https://doi.org/10.1186/s13071-024-06458-4 (chen2024establishmentofthe pages 1-2)

References

(dharmasiri2005thefboxprotein pages 2-3): Nihal Dharmasiri, Sunethra Dharmasiri, and Mark Estelle. The f-box protein tir1 is an auxin receptor. Nature, 435:441-445, May 2005. URL: https://doi.org/10.1038/nature03543, doi:10.1038/nature03543. This article has 2616 citations and is from a highest quality peer-reviewed journal.
(dharmasiri2005thefboxprotein pages 3-5): Nihal Dharmasiri, Sunethra Dharmasiri, and Mark Estelle. The f-box protein tir1 is an auxin receptor. Nature, 435:441-445, May 2005. URL: https://doi.org/10.1038/nature03543, doi:10.1038/nature03543. This article has 2616 citations and is from a highest quality peer-reviewed journal.
(dharmasiri2005thefboxprotein pages 1-2): Nihal Dharmasiri, Sunethra Dharmasiri, and Mark Estelle. The f-box protein tir1 is an auxin receptor. Nature, 435:441-445, May 2005. URL: https://doi.org/10.1038/nature03543, doi:10.1038/nature03543. This article has 2616 citations and is from a highest quality peer-reviewed journal.
(roij2024proteindegradationin pages 3-4): Martijn de Roij, Jan Willem Borst, and Dolf Weijers. Protein degradation in auxin response. The Plant Cell, 36:3025-3035, Apr 2024. URL: https://doi.org/10.1093/plcell/koae125, doi:10.1093/plcell/koae125. This article has 18 citations.
(vanneste2025mechanismsofauxin pages 10-13): Steffen Vanneste, Yuanrong Pei, and Jiří Friml. Mechanisms of auxin action in plant growth and development. Nature reviews. Molecular cell biology, May 2025. URL: https://doi.org/10.1038/s41580-025-00851-2, doi:10.1038/s41580-025-00851-2. This article has 76 citations.
(ang2023saveyourtirs pages 2-3): Aaron Chun Hou Ang and Lars Østergaard. Save your tirs – more to auxin than meets the eye. New Phytologist, 238:971-976, Feb 2023. URL: https://doi.org/10.1111/nph.18783, doi:10.1111/nph.18783. This article has 25 citations and is from a highest quality peer-reviewed journal.
(roij2024proteindegradationin pages 2-3): Martijn de Roij, Jan Willem Borst, and Dolf Weijers. Protein degradation in auxin response. The Plant Cell, 36:3025-3035, Apr 2024. URL: https://doi.org/10.1093/plcell/koae125, doi:10.1093/plcell/koae125. This article has 18 citations.
(roij2024proteindegradationin media 293a5f1a): Martijn de Roij, Jan Willem Borst, and Dolf Weijers. Protein degradation in auxin response. The Plant Cell, 36:3025-3035, Apr 2024. URL: https://doi.org/10.1093/plcell/koae125, doi:10.1093/plcell/koae125. This article has 18 citations.
(chaisupa2024understandingandengineering pages 134-138): P Chaisupa. Understanding and engineering chemically activated ubiquitin ligases for high-throughput detection, quantification, and control of molecules in yeast. Unknown journal, 2024.
(yu2012analysisofthe pages 37-43): H Yu. Analysis of the interaction between tir1/afbs and aux/iaas in arabidopsis thaliana. Unknown journal, 2012.
(yu2012analysisofthe pages 98-110): H Yu. Analysis of the interaction between tir1/afbs and aux/iaas in arabidopsis thaliana. Unknown journal, 2012.
(yu2012analysisofthe pages 132-146): H Yu. Analysis of the interaction between tir1/afbs and aux/iaas in arabidopsis thaliana. Unknown journal, 2012.
(shengjuan2024effectofmodulation pages 33-37): Shengjuan Li. Effect of modulation of auxin response on clubroot development caused by plasmodiophora brassicae in arabidopsis. Text, 2024. URL: https://doi.org/10.7939/r3-sz2t-g937, doi:10.7939/r3-sz2t-g937. This article has 1 citations and is from a peer-reviewed journal.
(prusinska2023thedifferentialbinding pages 4-5): Justyna Prusinska, Veselina Uzunova, Paul Schmitzer, Monte Weimer, Jared Bell, and Richard M. Napier. The differential binding and biological efficacy of auxin herbicides. Pest Management Science, 79:1305-1315, Dec 2023. URL: https://doi.org/10.1002/ps.7294, doi:10.1002/ps.7294. This article has 32 citations and is from a domain leading peer-reviewed journal.
(dubey2023theafb1auxin pages 4-5): Shiv Mani Dubey, Soeun Han, Nathan Stutzman, Michael J. Prigge, Eva Medvecká, Matthieu Pierre Platre, Wolfgang Busch, Matyáš Fendrych, and Mark Estelle. The afb1 auxin receptor controls the cytoplasmic auxin response pathway in arabidopsis thaliana. Molecular Plant, 16:1120-1130, Jul 2023. URL: https://doi.org/10.1016/j.molp.2023.06.008, doi:10.1016/j.molp.2023.06.008. This article has 74 citations and is from a highest quality peer-reviewed journal.
(dubey2023theafb1auxin pages 8-11): Shiv Mani Dubey, Soeun Han, Nathan Stutzman, Michael J. Prigge, Eva Medvecká, Matthieu Pierre Platre, Wolfgang Busch, Matyáš Fendrych, and Mark Estelle. The afb1 auxin receptor controls the cytoplasmic auxin response pathway in arabidopsis thaliana. Molecular Plant, 16:1120-1130, Jul 2023. URL: https://doi.org/10.1016/j.molp.2023.06.008, doi:10.1016/j.molp.2023.06.008. This article has 74 citations and is from a highest quality peer-reviewed journal.
(ang2023saveyourtirs pages 1-2): Aaron Chun Hou Ang and Lars Østergaard. Save your tirs – more to auxin than meets the eye. New Phytologist, 238:971-976, Feb 2023. URL: https://doi.org/10.1111/nph.18783, doi:10.1111/nph.18783. This article has 25 citations and is from a highest quality peer-reviewed journal.
(ogawa2024targetedproteindegradation pages 2-4): Yoshitaka Ogawa, Taisei P. Ueda, Keisuke Obara, Kohei Nishimura, and Takumi Kamura. Targeted protein degradation systems: controlling protein stability using e3 ubiquitin ligases in eukaryotic species. Cells, 13:175, Jan 2024. URL: https://doi.org/10.3390/cells13020175, doi:10.3390/cells13020175. This article has 9 citations.
(sharma2024protocolforauxininducible pages 1-3): Nidhi Sharma, Filipe Marques, and Paschalis Kratsios. Protocol for auxin-inducible protein degradation in c. elegans using different auxins and tir1-expressing strains. STAR Protocols, 5:103133, Sep 2024. URL: https://doi.org/10.1016/j.xpro.2024.103133, doi:10.1016/j.xpro.2024.103133. This article has 6 citations and is from a peer-reviewed journal.
(makino‐itou2024establishmentandcharacterization pages 1-2): Hatsune Makino‐Itou, Noriko Yamatani, Akemi Okubo, Makoto Kiso, Rieko Ajima, Masato T. Kanemaki, and Yumiko Saga. Establishment and characterization of mouse lines useful for endogenous protein degradation via an improved auxin‐inducible degron system (aid2). Development, Growth & Differentiation, 66:384-393, Sep 2024. URL: https://doi.org/10.1111/dgd.12942, doi:10.1111/dgd.12942. This article has 9 citations.
(chen2024establishmentofthe pages 1-2): Bo Chen, Qi Zhang, Sen Wang, Xing-ai Guan, Wan-xin Luo, Dong-fang Li, Yue He, Shu-jing Huang, Ya-ting Zhou, Jun-long Zhao, and Lan He. Establishment of the auxin inducible degron system for babesia duncani: a conditional knockdown tool to study precise protein regulation in babesia spp. Parasites & Vectors, Oct 2024. URL: https://doi.org/10.1186/s13071-024-06458-4, doi:10.1186/s13071-024-06458-4. This article has 1 citations and is from a peer-reviewed journal.
(vicencio2025engineeringtheauxininducible pages 1-3): Jeremy Vicencio, Daisuke Chihara, Matthias Eder, Julie Ahringer, and Nicholas Stroustrup. Engineering the auxin-inducible degron system for tunable in vivo control of organismal physiology. bioRxiv, Sep 2025. URL: https://doi.org/10.1101/2024.09.05.611487, doi:10.1101/2024.09.05.611487. This article has 1 citations.
(prusinska2023thedifferentialbinding pages 7-10): Justyna Prusinska, Veselina Uzunova, Paul Schmitzer, Monte Weimer, Jared Bell, and Richard M. Napier. The differential binding and biological efficacy of auxin herbicides. Pest Management Science, 79:1305-1315, Dec 2023. URL: https://doi.org/10.1002/ps.7294, doi:10.1002/ps.7294. This article has 32 citations and is from a domain leading peer-reviewed journal.
(ang2023saveyourtirs pages 4-5): Aaron Chun Hou Ang and Lars Østergaard. Save your tirs – more to auxin than meets the eye. New Phytologist, 238:971-976, Feb 2023. URL: https://doi.org/10.1111/nph.18783, doi:10.1111/nph.18783. This article has 25 citations and is from a highest quality peer-reviewed journal.
(su2023differentevolutionarypatterns pages 1-2): Liyao Su, Tian Zhang, Bin Yang, Tianyu Dong, Xiaoyu Liu, Yibo Bai, Hui Liu, Jingsong Xiong, Yan Zhong, and Zong-Ming Cheng. Different evolutionary patterns of tir1/afbs and aux/iaas and their implications for the morphogenesis of land plants. BMC Plant Biology, May 2023. URL: https://doi.org/10.1186/s12870-023-04253-4, doi:10.1186/s12870-023-04253-4. This article has 16 citations and is from a peer-reviewed journal.

Citations

prusinska2023thedifferentialbinding pages 4-5
dharmasiri2005thefboxprotein pages 2-3
ogawa2024targetedproteindegradation pages 2-4
sharma2024protocolforauxininducible pages 1-3
chen2024establishmentofthe pages 1-2
vicencio2025engineeringtheauxininducible pages 1-3
ang2023saveyourtirs pages 1-2
roij2024proteindegradationin pages 3-4
dharmasiri2005thefboxprotein pages 3-5
dharmasiri2005thefboxprotein pages 1-2
vanneste2025mechanismsofauxin pages 10-13
ang2023saveyourtirs pages 2-3
roij2024proteindegradationin pages 2-3
chaisupa2024understandingandengineering pages 134-138
yu2012analysisofthe pages 37-43
yu2012analysisofthe pages 98-110
yu2012analysisofthe pages 132-146
shengjuan2024effectofmodulation pages 33-37
prusinska2023thedifferentialbinding pages 7-10
ang2023saveyourtirs pages 4-5
su2023differentevolutionarypatterns pages 1-2
VIL
https://doi.org/10.1038/nature03543
https://doi.org/10.1111/nph.18783
https://doi.org/10.1016/j.molp.2023.06.008
https://doi.org/10.1093/plcell/koae125
https://doi.org/10.1002/ps.7294
https://doi.org/10.3390/cells13020175
https://doi.org/10.1016/j.xpro.2024.103133
https://doi.org/10.1111/dgd.12942
https://doi.org/10.1186/s13071-024-06458-4
https://doi.org/10.1038/nature03543,
https://doi.org/10.1093/plcell/koae125,
https://doi.org/10.1038/s41580-025-00851-2,
https://doi.org/10.1111/nph.18783,
https://doi.org/10.7939/r3-sz2t-g937,
https://doi.org/10.1002/ps.7294,
https://doi.org/10.1016/j.molp.2023.06.008,
https://doi.org/10.3390/cells13020175,
https://doi.org/10.1016/j.xpro.2024.103133,
https://doi.org/10.1111/dgd.12942,
https://doi.org/10.1186/s13071-024-06458-4,
https://doi.org/10.1101/2024.09.05.611487,
https://doi.org/10.1186/s12870-023-04253-4,

📄 View Raw YAML

id: Q570C0
gene_symbol: TIR1
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:3702
  label: Arabidopsis thaliana
description: >-
  TIR1 is the Arabidopsis F-box/LRR auxin receptor and substrate-recognition
  subunit of the SCF(TIR1) E3 ubiquitin ligase complex. Auxin binds the TIR1
  pocket and promotes recruitment of Aux/IAA transcriptional repressors,
  leading to their SCF-dependent degradation and auxin-regulated transcription.
  Lateral-root, stamen, phosphate-starvation, and other developmental phenotypes
  are downstream outputs of this auxin receptor and degradation mechanism.
existing_annotations:
- term:
    id: GO:0019005
    label: SCF ubiquitin ligase complex
  evidence_type: IDA
  original_reference_id: PMID:10398681
  review:
    summary: TIR1 is a component of SCF(TIR1) ubiquitin ligase complexes.
    action: ACCEPT
    reason: The SCF complex context is central to TIR1's auxin receptor/substrate-recognition function.
- term:
    id: GO:0000151
    label: ubiquitin ligase complex
  evidence_type: IDA
  original_reference_id: PMID:10398681
  review:
    summary: TIR1 is in a ubiquitin ligase complex, but the SCF-specific term is more precise.
    action: MODIFY
    reason: SCF ubiquitin ligase complex better captures the TIR1-containing complex.
    proposed_replacement_terms:
    - id: GO:0019005
      label: SCF ubiquitin ligase complex
- term:
    id: GO:0010011
    label: auxin binding
  evidence_type: IDA
  original_reference_id: PMID:17410169
  review:
    summary: Structural work shows auxin bound in the TIR1 receptor pocket.
    action: ACCEPT
    reason: Auxin binding is a direct molecular property of TIR1.
- term:
    id: GO:0010011
    label: auxin binding
  evidence_type: IDA
  original_reference_id: PMID:18391211
  review:
    summary: Auxin agonist/antagonist studies support ligand binding by TIR1.
    action: ACCEPT
    reason: Auxin binding is a direct molecular property of TIR1.
    supported_by:
    - reference_id: PMID:18391211
      supporting_text: their mode of action in binding to TIR1 is confirmed by x-ray crystallographic analysis
- term:
    id: GO:0038198
    label: auxin receptor activity
  evidence_type: IDA
  original_reference_id: PMID:15917797
  review:
    summary: TIR1 is an auxin receptor that mediates Aux/IAA degradation and auxin-regulated transcription.
    action: ACCEPT
    reason: Auxin receptor activity is the core molecular function of TIR1.
    supported_by:
    - reference_id: file:ARATH/TIR1/TIR1-deep-research-falcon.md
- term:
    id: GO:0000822
    label: inositol hexakisphosphate binding
  evidence_type: IDA
  original_reference_id: PMID:17410169
  review:
    summary: The TIR1 structure contains an inositol hexakisphosphate cofactor.
    action: KEEP_AS_NON_CORE
    reason: This is a supported cofactor-binding feature of the TIR1 receptor pocket, but the core molecular roles are auxin receptor and substrate-adaptor activity.
- term:
    id: GO:0004842
    label: ubiquitin-protein transferase activity
  evidence_type: IC
  original_reference_id: PMID:10398681
  review:
    summary: TIR1 contributes to SCF E3 ligase function as an F-box substrate receptor, but it is not the catalytic RING subunit.
    action: MODIFY
    reason: The term overstates TIR1's independent catalytic role; TIR1 is better represented as the auxin-dependent substrate adaptor of SCF(TIR1).
    proposed_replacement_terms:
    - id: GO:1990756
      label: ubiquitin-like ligase-substrate adaptor activity
- term:
    id: GO:0009734
    label: auxin-activated signaling pathway
  evidence_type: IMP
  original_reference_id: PMID:18391211
  review:
    summary: TIR1 mediates auxin-activated signaling through auxin-dependent Aux/IAA recruitment and degradation.
    action: ACCEPT
    reason: This is the central biological process controlled by TIR1.
    supported_by:
    - reference_id: PMID:18391211
      supporting_text: Auxin binding enhances the interaction between TIR1 and its substrates, the Aux/IAA repressors
- term:
    id: GO:0016036
    label: cellular response to phosphate starvation
  evidence_type: IEP
  original_reference_id: PMID:19106375
  review:
    summary: TIR1-dependent auxin sensitivity affects root responses to phosphate availability.
    action: KEEP_AS_NON_CORE
    reason: Phosphate starvation response is a physiological output of auxin signaling.
- term:
    id: GO:0010311
    label: lateral root formation
  evidence_type: IMP
  original_reference_id: PMID:9436980
  review:
    summary: tir1 mutants affect lateral root formation.
    action: KEEP_AS_NON_CORE
    reason: Lateral root formation is a downstream developmental output of auxin signaling.
- term:
    id: GO:0010152
    label: pollen maturation
  evidence_type: IGI
  original_reference_id: PMID:18628351
  review:
    summary: Auxin signaling through TIR1/AFB proteins contributes to pollen maturation.
    action: KEEP_AS_NON_CORE
    reason: Pollen maturation is a downstream reproductive output.
- term:
    id: GO:0009733
    label: response to auxin
  evidence_type: IMP
  original_reference_id: PMID:26236497
  review:
    summary: Altering TIR1 stability and SCF association changes auxin response.
    action: KEEP_AS_NON_CORE
    reason: The response term is correct but less mechanistic than auxin receptor activity and auxin-activated signaling.
- term:
    id: GO:0009733
    label: response to auxin
  evidence_type: IMP
  original_reference_id: PMID:9436980
  review:
    summary: tir1 mutants are deficient in auxin response phenotypes.
    action: KEEP_AS_NON_CORE
    reason: The response term is correct but less mechanistic than auxin receptor activity and auxin-activated signaling.
- term:
    id: GO:0048443
    label: stamen development
  evidence_type: IGI
  original_reference_id: PMID:18628351
  review:
    summary: Auxin signaling through TIR1/AFB proteins contributes to stamen development.
    action: KEEP_AS_NON_CORE
    reason: Stamen development is a downstream reproductive output.
- term:
    id: GO:0006511
    label: ubiquitin-dependent protein catabolic process
  evidence_type: TAS
  original_reference_id: PMID:11019805
  review:
    summary: TIR1 participates in ubiquitin-dependent degradation, but the SCF-dependent term is more precise.
    action: MODIFY
    reason: TIR1 functions in SCF-dependent Aux/IAA degradation rather than generic ubiquitin-dependent catabolism.
    proposed_replacement_terms:
    - id: GO:0031146
      label: SCF-dependent proteasomal ubiquitin-dependent protein catabolic process
- term:
    id: GO:0031146
    label: SCF-dependent proteasomal ubiquitin-dependent protein catabolic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: TIR1 family context supports SCF-dependent proteasomal degradation of Aux/IAA repressors.
    action: ACCEPT
    reason: This is the core mechanistic process downstream of auxin-bound TIR1.
references:
- id: PMID:10398681
  title: Identification of an SCF ubiquitin-ligase complex required for auxin response in Arabidopsis thaliana.
  findings: []
- id: PMID:11019805
  title: Protein degradation in signaling.
  findings: []
- id: PMID:11713520
  title: Auxin regulates SCF(TIR1)-dependent degradation of AUX/IAA proteins.
  findings: []
- id: PMID:15917797
  title: The F-box protein TIR1 is an auxin receptor.
  findings: []
- id: PMID:15917798
  title: The Arabidopsis F-box protein TIR1 is an auxin receptor.
  findings: []
- id: PMID:17410169
  title: Mechanism of auxin perception by the TIR1 ubiquitin ligase.
  findings: []
- id: PMID:18391211
  title: Small-molecule agonists and antagonists of F-box protein-substrate interactions in auxin perception and signaling.
  findings: []
- id: PMID:18628351
  title: Auxin regulates Arabidopsis anther dehiscence, pollen maturation, and filament elongation.
  findings: []
- id: PMID:19106375
  title: Phosphate availability alters lateral root development in Arabidopsis by modulating auxin sensitivity via a mechanism involving the TIR1 auxin receptor.
  findings: []
- id: PMID:26236497
  title: Untethering the TIR1 auxin receptor from the SCF complex increases its stability and inhibits auxin response.
  findings: []
- id: PMID:9436980
  title: The TIR1 protein of Arabidopsis functions in auxin response and is related to human SKP2 and yeast grr1p.
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: file:ARATH/TIR1/TIR1-uniprot.txt
  title: UniProt record for Arabidopsis TIR1
  findings:
  - statement: TIR1 is described as an auxin receptor and SCF(TIR1) component.
- id: file:ARATH/TIR1/TIR1-deep-research-falcon.md
  title: Falcon deep research report for Arabidopsis TIR1
  findings:
  - statement: Falcon research supports TIR1 as an F-box/LRR auxin receptor and SCF substrate adaptor for Aux/IAA degradation.
- id: file:interpro/panther/PTHR16134/PTHR16134-entries.csv
  title: PANTHER PTHR16134 entries
  findings:
  - statement: TIR1 and COI1 are in distinct F-box/LRR subfamilies, avoiding auxin/jasmonate receptor conflation.
core_functions:
- description: >-
    Auxin receptor and F-box substrate-recognition role within SCF(TIR1). TIR1
    binds auxin and Aux/IAA substrates, promoting SCF-dependent degradation of
    Aux/IAA repressors and activation of auxin-regulated transcription.
  molecular_function:
    id: GO:0038198
    label: auxin receptor activity
  directly_involved_in:
  - id: GO:0009734
    label: auxin-activated signaling pathway
  in_complex:
    id: GO:0019005
    label: SCF ubiquitin ligase complex
  supported_by:
  - reference_id: file:ARATH/TIR1/TIR1-uniprot.txt
    supporting_text: Auxin receptor that mediates Aux/IAA proteins proteasomal
  - reference_id: file:ARATH/TIR1/TIR1-uniprot.txt
    supporting_text: Part of a SCF E3 ubiquitin ligase
  - reference_id: PMID:15917797
    supporting_text: TIR1 is an auxin receptor that mediates Aux/IAA degradation and
    reference_section_type: ABSTRACT
  - reference_id: PMID:17410169
    supporting_text: recognizes auxin and the Aux/IAA polypeptide substrate through a single surface
    reference_section_type: ABSTRACT
  - reference_id: file:interpro/panther/PTHR16134/PTHR16134-entries.csv
    supporting_text: Q570C0,Protein TRANSPORT INHIBITOR RESPONSE 1
- description: >-
    Auxin-dependent F-box substrate adaptor activity in SCF(TIR1). TIR1 binds
    Aux/IAA repressors in an auxin-stabilized pocket and presents them for
    SCF-dependent ubiquitination and degradation.
  molecular_function:
    id: GO:1990756
    label: ubiquitin-like ligase-substrate adaptor activity
  directly_involved_in:
  - id: GO:0031146
    label: SCF-dependent proteasomal ubiquitin-dependent protein catabolic process
  in_complex:
    id: GO:0019005
    label: SCF ubiquitin ligase complex
  supported_by:
  - reference_id: PMID:18391211
    supporting_text: TIR1 is the substrate receptor of the ubiquitin-ligase complex SCF(TIR1).
    reference_section_type: ABSTRACT
  - reference_id: PMID:17410169
    supporting_text: recognizes auxin and the Aux/IAA polypeptide substrate through a single surface
    reference_section_type: ABSTRACT
  - reference_id: file:ARATH/TIR1/TIR1-uniprot.txt
    supporting_text: Auxin receptor that mediates Aux/IAA proteins proteasomal
proposed_new_terms: []
suggested_questions:
- question: Should GO annotation distinguish TIR1's substrate-recognition contribution to E3 ligase activity from catalytic ubiquitin-protein transferase activity?
- question: Which TIR1/AFB developmental phenotypes should be represented directly versus modeled as downstream auxin transcriptional outputs?
suggested_experiments:
- description: Quantify native TIR1-dependent Aux/IAA degradation kinetics across auxin analogs and SCF assembly mutants.
- description: Compare TIR1 versus related AFB subfamily members for substrate specificity and developmental-output specificity.

TIR1

Gene Description

Existing Annotations Review

Core Functions

Auxin receptor and F-box substrate-recognition role within SCF(TIR1). TIR1 binds auxin and Aux/IAA substrates, promoting SCF-dependent degradation of Aux/IAA repressors and activation of auxin-regulated transcription.

Auxin-dependent F-box substrate adaptor activity in SCF(TIR1). TIR1 binds Aux/IAA repressors in an auxin-stabilized pocket and presents them for SCF-dependent ubiquitination and degradation.