PIN3 is a homodimeric auxin efflux transporter that redistributes indole-3-acetic acid across the Arabidopsis plasma membrane. Its cell-type-specific polarity and regulated vesicular trafficking direct lateral auxin redistribution during gravitropism and phototropism. Phosphorylation of the central hydrophilic loop regulates trafficking and transport-associated developmental responses. PIN3 also contributes to auxin distribution in developing seeds and to root development; its polarity and physiological effects depend on tissue and stimulus rather than a single fixed membrane face.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005739 mitochondrion | HDA PMID:28887381 Global Analysis of Membrane-associated Protein Oligomerizati... | UNDECIDED | Summary: The cited microsomal proteome does not resolve mitochondrial residence of PIN3. Reason: The actual PMID28887381 supplementary Mapp entry AT1G70940 (Excel1879) classifies PIN3 as a true membrane protein with a plasma-membrane SUBAcon assignment and no dual-location flag. That classification is not a mitochondrial localization assay. The independent PM evidence does not exclude an additional mitochondrial pool; retain uncertainty about this specific HDA claim rather than deleting it because the canonical location differs. Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. file:ARATH/ABCB19/ABCB19-bioinformatics/README.md PIN3 AT1G70940.1 appears in S1 row 1879 with the same membrane/blank-dual/PM summary. |
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | UNDECIDED | Summary: The inherited ER location remains unresolved for long-loop PIN3. Reason: PTN001589272 propagates ER localization across a PIN lineage containing organellar and PM transporters. Native PIN3 imaging establishes PM and cycling vesicles, but does not exclude an ER pool. The source set includes short-loop PIN proteins with different localization; neither that distinction nor possible biosynthetic transit establishes whether PIN3 has the asserted ER residence. Do not override the ancestral location solely from PM predominance. Propagation Review Root cause: UNRESOLVED Sources checked: PANTHER:PTN001589272 UNRESOLVED Native PIN3 ER residence has not been resolved; PM/cycling-vesicle evidence alone does not disprove the inherited location. Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. |
| GO:0005886 plasma membrane | EXP PMID:20439545 Differential auxin-transporting activities of PIN-FORMED pro... | ACCEPT | Summary: PIN3 is localized at the plasma membrane. Reason: Native tropism imaging directly establishes the PM location, independently corroborating the phylogenetic and electronic rows. Root-hair expression and phosphovariant studies add tissue/construct-specific observations; they do not imply a fixed polarity in every cell. Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. |
| GO:0005886 plasma membrane | IBA GO_REF:0000033 | ACCEPT | Summary: PIN3 is localized at the plasma membrane. Reason: Native tropism imaging directly establishes the PM location, independently corroborating the phylogenetic and electronic rows. Root-hair expression and phosphovariant studies add tissue/construct-specific observations; they do not imply a fixed polarity in every cell. Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. |
| GO:0005886 plasma membrane | IDA PMID:11845211 Lateral relocation of auxin efflux regulator PIN3 mediates t... | ACCEPT | Summary: PIN3 is localized at the plasma membrane. Reason: Native tropism imaging directly establishes the PM location, independently corroborating the phylogenetic and electronic rows. Root-hair expression and phosphovariant studies add tissue/construct-specific observations; they do not imply a fixed polarity in every cell. Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. |
| GO:0005886 plasma membrane | IDA PMID:22519832 Functional identification of the phosphorylation sites of Ar... | ACCEPT | Summary: PIN3 is localized at the plasma membrane. Reason: Native tropism imaging directly establishes the PM location, independently corroborating the phylogenetic and electronic rows. Root-hair expression and phosphovariant studies add tissue/construct-specific observations; they do not imply a fixed polarity in every cell. Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: PIN3 is localized at the plasma membrane. Reason: Native tropism imaging directly establishes the PM location, independently corroborating the phylogenetic and electronic rows. Root-hair expression and phosphovariant studies add tissue/construct-specific observations; they do not imply a fixed polarity in every cell. Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. |
| GO:0009416 response to light stimulus | IDA PMID:21394084 Light-mediated polarization of the PIN3 auxin transporter fo... | KEEP AS NON CORE | Summary: Light-induced PIN3 polarization contributes to phototropic growth. Reason: The transporter redistributes auxin downstream of light perception in hypocotyl endodermis. Retain response to light without calling PIN3 a photoreceptor or assuming the same trafficking response in every tissue. Supporting Evidence: PMID:21394084 light polarizes the cellular localization of the auxin efflux carrier PIN3 in hypocotyl endodermis cells |
| GO:0009606 tropism | IMP PMID:11845211 Lateral relocation of auxin efflux regulator PIN3 mediates t... | ACCEPT | Summary: PIN3-dependent auxin redistribution mediates tropic growth. Reason: The original mutant and localization evidence links the carrier to differential growth following directional stimuli; this is a mechanistic transport contribution to tropism rather than a generic growth association. Supporting Evidence: PMID:11845211 In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. PMID:21394084 light polarizes the cellular localization of the auxin efflux carrier PIN3 in hypocotyl endodermis cells |
| GO:0009630 gravitropism | IBA GO_REF:0000033 | ACCEPT | Summary: PIN3 relocalization supports gravitropic auxin redistribution. Reason: Native PIN3 moves laterally in gravity-sensing columella cells and pin3 mutations alter gravitropic growth. PMID16141452 discusses PIN3 within a broader brassinosteroid/PAT study; its PIN2/ROP2-centered experiments do not invalidate the independently demonstrated PIN3 function or imply direct BR sensing by PIN3. Supporting Evidence: PMID:11845211 In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. |
| GO:0009630 gravitropism | TAS PMID:16141452 Brassinosteroids stimulate plant tropisms through modulation... | ACCEPT | Summary: PIN3 relocalization supports gravitropic auxin redistribution. Reason: Native PIN3 moves laterally in gravity-sensing columella cells and pin3 mutations alter gravitropic growth. PMID16141452 discusses PIN3 within a broader brassinosteroid/PAT study; its PIN2/ROP2-centered experiments do not invalidate the independently demonstrated PIN3 function or imply direct BR sensing by PIN3. Supporting Evidence: PMID:11845211 In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. |
| GO:0009926 auxin polar transport | IBA GO_REF:0000033 | ACCEPT | Summary: PIN3 efflux and regulated polarity contribute to directional auxin movement. Reason: The carrier supplies a physical auxin export step, and stimulus-dependent relocation redirects the tissue-level flux. The inherited polar-transport claim is concordant with direct PIN3 experiments; polarity is specified by cell type and stimulus, not an invariant basal orientation. Supporting Evidence: PMID:11845211 In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. PMID:16731587 In an auxin efflux assay using transgenic tobacco suspension cells, PIDox or PIN3ox also enhanced auxin efflux. |
| GO:0009926 auxin polar transport | IMP PMID:11845211 Lateral relocation of auxin efflux regulator PIN3 mediates t... | ACCEPT | Summary: PIN3 efflux and regulated polarity contribute to directional auxin movement. Reason: The carrier supplies a physical auxin export step, and stimulus-dependent relocation redirects the tissue-level flux. The inherited polar-transport claim is concordant with direct PIN3 experiments; polarity is specified by cell type and stimulus, not an invariant basal orientation. Supporting Evidence: PMID:11845211 In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. PMID:16731587 In an auxin efflux assay using transgenic tobacco suspension cells, PIDox or PIN3ox also enhanced auxin efflux. |
| GO:0009958 positive gravitropism | IMP PMID:22519832 Functional identification of the phosphorylation sites of Ar... | ACCEPT | Summary: PIN3 phosphorylation-dependent trafficking contributes to root positive gravitropism. Reason: The cited phosphosite study includes root gravitropic defects alongside impaired trafficking and transport. Retain the root-directed tropic process while distinguishing it from shoot phototropism. Supporting Evidence: PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. PMID:11845211 In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. |
| GO:0009986 cell surface | IDA PMID:16731587 PINOID positively regulates auxin efflux in Arabidopsis root... | ACCEPT | Summary: PIN3 is present at the cell surface. Reason: PIN3-GFP cell-boundary imaging and independent native plasma-membrane localization support this spatial claim. Cell surface describes position at the cell boundary; it is not interchangeable with a claim of extracellular secretion. Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. PMID:16731587 PIN3-GFP localized to the cellular boundary in both Arabidopsis root hair cells and tobacco BY-2 cells |
| GO:0010315 auxin export across the plasma membrane | IDA PMID:35917926 Structures and mechanisms of the Arabidopsis auxin transport... | ACCEPT | Summary: PIN3 mediates auxin export from cells. Reason: Direct radiolabeled auxin efflux and the PIN3 structure/function study establish cellular export. Phosphosite mutants alter trafficking and export-associated phenotypes, but those perturbations alone are not used to assign a different transport substrate. Supporting Evidence: PMID:16731587 In an auxin efflux assay using transgenic tobacco suspension cells, PIDox or PIN3ox also enhanced auxin efflux. url:https://www.nature.com/articles/s41586-022-05142-w The 3H-IAA efflux of WT and mutant PIN3 at 10 min in the IAA loading phase in the absence or presence of 50 µM NPA PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. |
| GO:0010315 auxin export across the plasma membrane | IMP PMID:22519832 Functional identification of the phosphorylation sites of Ar... | ACCEPT | Summary: PIN3 mediates auxin export from cells. Reason: Direct radiolabeled auxin efflux and the PIN3 structure/function study establish cellular export. Phosphosite mutants alter trafficking and export-associated phenotypes, but those perturbations alone are not used to assign a different transport substrate. Supporting Evidence: PMID:16731587 In an auxin efflux assay using transgenic tobacco suspension cells, PIDox or PIN3ox also enhanced auxin efflux. url:https://www.nature.com/articles/s41586-022-05142-w The 3H-IAA efflux of WT and mutant PIN3 at 10 min in the IAA loading phase in the absence or presence of 50 µM NPA PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. |
| GO:0010329 auxin efflux transmembrane transporter activity | IBA GO_REF:0000033 | ACCEPT | Summary: PIN3 has auxin efflux transmembrane transporter activity. Reason: Direct IAA transport and ligand-bound structure/function evidence establish this activity, independently supporting the PAINT row and the seed-development annotation. PMID36648165 adds polar PIN3 localization and auxin-distribution effects in the seed coat; it is not the sole basis for the molecular activity. Supporting Evidence: PMID:16731587 In an auxin efflux assay using transgenic tobacco suspension cells, PIDox or PIN3ox also enhanced auxin efflux. url:https://www.nature.com/articles/s41586-022-05142-w The 3H-IAA efflux of WT and mutant PIN3 at 10 min in the IAA loading phase in the absence or presence of 50 µM NPA |
| GO:0010329 auxin efflux transmembrane transporter activity | IDA PMID:35917926 Structures and mechanisms of the Arabidopsis auxin transport... | ACCEPT | Summary: PIN3 has auxin efflux transmembrane transporter activity. Reason: Direct IAA transport and ligand-bound structure/function evidence establish this activity, independently supporting the PAINT row and the seed-development annotation. PMID36648165 adds polar PIN3 localization and auxin-distribution effects in the seed coat; it is not the sole basis for the molecular activity. Supporting Evidence: PMID:16731587 In an auxin efflux assay using transgenic tobacco suspension cells, PIDox or PIN3ox also enhanced auxin efflux. url:https://www.nature.com/articles/s41586-022-05142-w The 3H-IAA efflux of WT and mutant PIN3 at 10 min in the IAA loading phase in the absence or presence of 50 µM NPA |
| GO:0010329 auxin efflux transmembrane transporter activity | IMP PMID:36648165 Biosynthesis- and transport-mediated dynamic auxin distribut... | ACCEPT | Summary: PIN3 has auxin efflux transmembrane transporter activity. Reason: Direct IAA transport and ligand-bound structure/function evidence establish this activity, independently supporting the PAINT row and the seed-development annotation. PMID36648165 adds polar PIN3 localization and auxin-distribution effects in the seed coat; it is not the sole basis for the molecular activity. Supporting Evidence: PMID:16731587 In an auxin efflux assay using transgenic tobacco suspension cells, PIDox or PIN3ox also enhanced auxin efflux. url:https://www.nature.com/articles/s41586-022-05142-w The 3H-IAA efflux of WT and mutant PIN3 at 10 min in the IAA loading phase in the absence or presence of 50 µM NPA |
| GO:0012506 vesicle membrane | IDA PMID:11845211 Lateral relocation of auxin efflux regulator PIN3 mediates t... | ACCEPT | Summary: PIN3 cycles through vesicular membranes. Reason: The native localization study explicitly observes actin-dependent cycling vesicles as well as PM-localized PIN3. This is compatible with trafficking regulation and does not identify every vesicle as ER or a specific endosomal subtype. Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. |
| GO:0016020 membrane | IEA GO_REF:0000120 | MODIFY | Summary: The general membrane term can be resolved to plasma and vesicle membranes. Reason: Native imaging supports both the functional PM pool and cycling vesicles. Refine the broad domain-derived membrane claim to both existing specific locations, avoiding an artificial exclusive-PM interpretation. Proposed replacements: plasma membrane vesicle membrane Supporting Evidence: PMID:11845211 PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. |
| GO:0016328 lateral plasma membrane | IDA PMID:11845211 Lateral relocation of auxin efflux regulator PIN3 mediates t... | ACCEPT | Summary: PIN3 occupies lateral plasma-membrane domains in defined tissues and responses. Reason: The original study explicitly observes lateral surface accumulation and gravity-induced lateral relocation. This location is contextual; columella PIN3 can be symmetric before stimulation and other tissues use different polarity. Supporting Evidence: PMID:11845211 In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. PMID:11845211 PIN3 protein accumulating predominantly at the lateral cell surface. |
| GO:0042802 identical protein binding | IDA PMID:35917926 Structures and mechanisms of the Arabidopsis auxin transport... | ACCEPT | Summary: PIN3 forms a structurally resolved homodimer. Reason: The cryo-EM structure identifies a scaffold-domain dimer interface, and the associated source includes dimer-interface mutant chromatography/native PAGE. Retain self-association without inferring that every PIN isoform or every transport state has identical oligomeric requirements. Supporting Evidence: PMID:35917926 A. thaliana PIN3 exists as a homodimer, and its transmembrane helices 1, 2 and 7 in the scaffold domain are involved in dimerization. |
| GO:0042803 protein homodimerization activity | IDA PMID:35917926 Structures and mechanisms of the Arabidopsis auxin transport... | ACCEPT | Summary: PIN3 forms a structurally resolved homodimer. Reason: The cryo-EM structure identifies a scaffold-domain dimer interface, and the associated source includes dimer-interface mutant chromatography/native PAGE. Retain self-association without inferring that every PIN isoform or every transport state has identical oligomeric requirements. Supporting Evidence: PMID:35917926 A. thaliana PIN3 exists as a homodimer, and its transmembrane helices 1, 2 and 7 in the scaffold domain are involved in dimerization. |
| GO:0048364 root development | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: PIN3-dependent auxin distribution contributes to root development. Reason: The phosphosite study connects altered PIN3 trafficking to root-growth and auxin-maxima defects. The inherited developmental claim is concordant with target biology, but root development is a contextual physiological consequence of the transport activity rather than a distinct molecular mechanism. Supporting Evidence: PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. |
| GO:0048364 root development | IMP PMID:22519832 Functional identification of the phosphorylation sites of Ar... | KEEP AS NON CORE | Summary: PIN3-dependent auxin distribution contributes to root development. Reason: The phosphosite study connects altered PIN3 trafficking to root-growth and auxin-maxima defects. The inherited developmental claim is concordant with target biology, but root development is a contextual physiological consequence of the transport activity rather than a distinct molecular mechanism. Supporting Evidence: PMID:22519832 Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. |
| GO:0048766 root hair initiation | IMP PMID:16731587 PINOID positively regulates auxin efflux in Arabidopsis root... | MARK AS OVER ANNOTATED | Summary: Reduced hair counts after PIN3 overexpression do not specifically establish a normal root-hair initiation role. Reason: The full study measures number and length of visible hairs in root-hair-specific PIN3 overexpressors and shows auxin-rescuable inhibition. It does not isolate an initiation-stage mechanism or distinguish uninitiated hairs from severely growth-inhibited hairs. The measured effect supports auxin-dependent hair growth regulation, but the initiation-specific annotation exceeds that resolution. Supporting Evidence: PMID:16731587 All 52 T1 PIN3ox transformants exhibited reduced length and number of root hairs |
| GO:0048767 root hair elongation | IMP PMID:16731587 PINOID positively regulates auxin efflux in Arabidopsis root... | KEEP AS NON CORE | Summary: PIN3-mediated auxin efflux can regulate root-hair elongation. Reason: Root-hair-specific PIN3 overexpression shortens hairs, and auxin or efflux inhibition restores growth; the paper also detects endogenous PIN3 transcript in hair-cell RNA. Retain the elongation relationship with its gain-of-function context rather than claiming an exclusive native requirement. Supporting Evidence: PMID:16731587 All 52 T1 PIN3ox transformants exhibited reduced length and number of root hairs PMID:16731587 The addition of IAA fully restored root hairs in the PIN3ox root |
| GO:0055085 transmembrane transport | IEA GO_REF:0000002 | MODIFY | Summary: Broad transmembrane transport is specifically auxin export. Reason: Direct cellular IAA efflux identifies the substrate and outward direction, permitting refinement of the transporter-domain process mapping to the existing auxin-export term. Proposed replacements: auxin export across the plasma membrane Supporting Evidence: PMID:16731587 In an auxin efflux assay using transgenic tobacco suspension cells, PIDox or PIN3ox also enhanced auxin efflux. |
| GO:0060918 auxin transport | IEA GO_REF:0000117 | ACCEPT | Summary: PIN3 carries auxin and contributes to its redistribution. Reason: The pathway-level auxin-transport annotation remains informative alongside the cellular export activity: native polarity and regulated trafficking determine intercellular redistribution. It is not removed or treated as non-core merely because a narrower export term is also present. Supporting Evidence: PMID:16731587 In an auxin efflux assay using transgenic tobacco suspension cells, PIDox or PIN3ox also enhanced auxin efflux. PMID:11845211 In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. |
| GO:0071469 cellular response to alkaline pH | IDA PMID:36582637 Alkaline stress reduces root waving by regulating PIN7 vacuo... | REMOVE | Summary: PIN3 is the tested negative comparator in the cited alkaline-stress mechanism. Reason: The complete study compares PIN3 and PIN7: PIN3 membrane localization does not significantly change at pH8 and pin3-4 responds similarly to controls, whereas PIN7 vacuolar transport and pin7 phenotype establish the mechanism. GO:0071469 requires a cellular change attributable to alkaline pH; the actual PIN3 comparisons do not support that positive claim. This source-based correction is not inferred from the PIN7-focused title and does not assert that PIN3 can never contribute in another alkaline-stress context. Supporting Evidence: PMID:36582637 we did not detect significant change of PIN3 membrane localization at pH 8.0 PMID:36582637 the pin3-4 (Young et al., 2006) mutants exhibited a similar response to alkaline stress as the control seedlings |
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