PIN1

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005886 plasma membrane	IEA GO_REF:0000044	ACCEPT	Summary: PIN1 is an integral plasma-membrane auxin efflux carrier; the plasma membrane is its functional location. This UniProt subcellular-location mapping is fully consistent with experimental evidence. Reason: The plasma membrane is the bona fide functional compartment of PIN1, confirmed by multiple experimental studies; this is a core localization. Supporting Evidence: PMID:33705718 PINs, MAB4/MELs, and AGC kinases interact in the same complex at the plasma membrane.
GO:0016020 membrane	IEA GO_REF:0000002	KEEP AS NON CORE	Summary: Generic membrane localization from InterPro mapping. PIN1 is a multi-pass membrane protein, so the term is correct but far less informative than the plasma-membrane annotation. Reason: Correct but a broad parent of the more specific (and experimentally supported) plasma membrane term; retained as non-core background. Supporting Evidence: PMID:35917925 The transmembrane domain of PIN1 has ten transmembrane segments (TM1 to TM10), with both N and C termini located extracellularly
GO:0055085 transmembrane transport	IEA GO_REF:0000002	KEEP AS NON CORE	Summary: PIN1 mediates transmembrane transport of auxin across the plasma membrane. The term is correct but is a broad parent of the more specific auxin export and polar auxin transport terms. Reason: Accurate but generic; the more precise auxin-transport terms capture the core function. Retained as a correct broad parent. Supporting Evidence: PMID:35917925 These results show that PIN1 mediates active auxin efflux when expressed in HEK293F cells, and is further activated by D6PK.
GO:0060918 auxin transport	IEA GO_REF:0000117	ACCEPT	Summary: PIN1 is the founding auxin efflux carrier and a central mediator of auxin transport. This ARBA electronic annotation is well supported. Reason: Core biological process; PIN1-mediated efflux is rate-limiting for cellular auxin transport. Supporting Evidence: PMID:9856939 Mutations affecting the PIN-FORMED (PIN1) gene diminish polar auxin transport in Arabidopsis thaliana inflorescence axes. file:ARATH/PIN1/PIN1-deep-research-falcon.md demonstrates PIN1-mediated auxin (IAA) efflux and inhibitor (NPA) binding, matching the UniProt record provided.
GO:0005515 protein binding	IPI PMID:17237354 Interactions among PIN-FORMED and P-glycoprotein auxin trans...	MARK AS OVER ANNOTATED	Summary: IntAct interaction with ABCB19/PGP19 (Q9LJX0), a P-glycoprotein auxin transporter that co-acts with PIN1 in directional auxin transport. The bare protein binding term is uninformative about molecular function. Reason: The interaction with ABCB19 is real and biologically relevant to auxin transport, but GO:0005515 is too generic to convey function; per curation guidance bare protein binding is not retained as a core molecular function. Supporting Evidence: PMID:17237354 Specific PGP–PIN interactions were seen in yeast two-hybrid and coimmunoprecipitation assays.
GO:0005515 protein binding	IPI PMID:17889649 Antagonistic regulation of PIN phosphorylation by PP2A and P...	UNDECIDED	Summary: IntAct interaction with PINOID/PID (O64682), the AGC kinase that phosphorylates the PIN1 hydrophilic loop to control apical-basal polarity. The generic protein binding term is uninformative. Reason: The cited publication (PMID:17889649) is available only as an abstract that describes PP2A/PINOID colocalization with and antagonistic phosphorylation of PINs; it does not report a direct physical PIN1-PID binding assay, so it does not substantiate this GO:0005515 (protein binding) IPI annotation. No verbatim supporting passage for a PIN1-PID interaction could be extracted.
GO:0005515 protein binding	IPI PMID:20080776 PIN phosphorylation is sufficient to mediate PIN polarity an...	UNDECIDED	Summary: IntAct interaction with PID (O64682) in the context of phosphorylation directing PIN polarity. Generic protein binding term is uninformative. Reason: The cited publication (PMID:20080776) characterizes a conserved phosphorylation site that controls PIN polarity and explicitly reports that its in vitro results do NOT support this site being a PID target; it does not report a direct physical PIN1-PID binding assay and therefore does not substantiate this GO:0005515 (protein binding) IPI annotation. No verbatim supporting passage for a PIN1-PID interaction could be extracted.
GO:0005886 plasma membrane	EXP PMID:20439545 Differential auxin-transporting activities of PIN-FORMED pro...	ACCEPT	Summary: Experimental localization of PIN1 to the plasma membrane in root hair cells, consistent with its function as a PM auxin efflux carrier. Reason: Direct experimental support for the core plasma-membrane localization. Supporting Evidence: PMID:20439545 those PINs were localized in the plasma membrane, where they likely export auxin to the apoplast
GO:0042802 identical protein binding	IDA PMID:35917925 Structural insights into auxin recognition and efflux by Ara...	ACCEPT	Summary: Cryo-EM shows PIN1 forms a homodimer with a TM1/TM2/TM7 dimer interface. Identical protein binding (self-association) is directly demonstrated. Reason: Directly supported by the structure; a genuine, informative molecular property (self-interaction), retained as a non-core but real activity. Supporting Evidence: PMID:35917925 we determined a dimeric structure of PIN1
GO:0042803 protein homodimerization activity	IDA PMID:35917925 Structural insights into auxin recognition and efflux by Ara...	ACCEPT	Summary: PIN1 assembles as a homodimer in the cryo-EM structure, with TM1, TM2 and TM7 forming the dimer interface. Reason: Structurally established homodimerization; an informative molecular function (more specific than identical protein binding). Supporting Evidence: PMID:35917925 TM1, TM2 and TM7 constitute the dimer interface, which consists mainly of hydrophobic residues
GO:0010315 auxin export across the plasma membrane	IDA PMID:35917925 Structural insights into auxin recognition and efflux by Ara...	ACCEPT	Summary: PIN1 expressed in HEK293F cells mediates active IAA efflux across the plasma membrane (enhanced by D6PK, inhibited by NPA). This is the most precise biological-process term for the PIN1 efflux event. Reason: Directly demonstrated auxin export across the PM; a core process. Supporting Evidence: PMID:35917925 These results show that PIN1 mediates active auxin efflux when expressed in HEK293F cells, and is further activated by D6PK. This PIN1-mediated auxin efflux is inhibited by NPA file:ARATH/PIN1/PIN1-deep-research-falcon.md that exports auxin from the cytosol toward the apoplast, thereby enabling
GO:0010329 auxin efflux transmembrane transporter activity	IDA PMID:35917925 Structural insights into auxin recognition and efflux by Ara...	ACCEPT	Summary: Heterologous reconstitution plus cryo-EM with bound IAA establish PIN1 as a direct auxin efflux transmembrane transporter; IAA is coordinated in an intracellular pocket by conserved residues (V51, N112, N478, I582) and mutation of these residues impairs efflux activity. This is the core molecular function. Reason: Strongest, most informative MF annotation; directly supported by structure-function evidence. Supporting Evidence: PMID:35917925 In the structure, IAA is coordinated through both hydrogen bonding and hydrophobic interactions PMID:35917925 All interacting residues (V51, N112, N478 and I582) are highly conserved in PINs file:ARATH/PIN1/PIN1-deep-research-falcon.md Arabidopsis PIN1 was solved in multiple inward-facing conformations (apo, IAA-bound, NPA-bound), revealing a conserved transporter fold and a defined intracellular binding pocket that coordinates IAA. file:ARATH/PIN1/PIN1-deep-research-falcon.md this provides a molecular definition of PIN1’s substrate recognition.
GO:0005515 protein binding	IPI PMID:33705718 AGC kinases and MAB4/MEL proteins maintain PIN polarity by l...	MARK AS OVER ANNOTATED	Summary: IntAct/UniProt interaction with NPY5/MEL1 (Q0WL52), a MAB4/MEL adaptor recruited to the plasma membrane by PIN1 to maintain polarity. Generic protein binding term is uninformative. Reason: The PIN1-NPY5/MEL1 interaction is mechanistically important for polarity maintenance, but GO:0005515 conveys no specific function. Supporting Evidence: PMID:33705718 MAB4/MELs are recruited to the plasma membrane by the PINs and in concert with the AGC kinases maintain PIN polarity
GO:0071944 cell periphery	IDA PMID:33705718 AGC kinases and MAB4/MEL proteins maintain PIN polarity by l...	KEEP AS NON CORE	Summary: PIN1 localizes to the cell periphery (plasma membrane and polar PM domains). Correct but a broad parent of the specific plasma-membrane term. Reason: Accurate but generic relative to the plasma-membrane and polar-domain annotations; retained as non-core. Supporting Evidence: PMID:33705718 the polar subcellular plasma membrane (PM) localization of the PIN-FORMED (PIN) auxin efflux carriers
GO:0005886 plasma membrane	IDA PMID:33705718 AGC kinases and MAB4/MEL proteins maintain PIN polarity by l...	ACCEPT	Summary: Direct experimental confirmation of PIN1 plasma-membrane localization within the PIN-MAB4/MEL-AGC kinase complex. Reason: Core localization with direct experimental support. Supporting Evidence: PMID:33705718 we demonstrate that PINs, MAB4/MELs, and AGC kinases interact in the same complex at the plasma membrane
GO:0016324 apical plasma membrane	IDA PMID:33705718 AGC kinases and MAB4/MEL proteins maintain PIN polarity by l...	KEEP AS NON CORE	Summary: PIN1 occupies polar (apical or basal) plasma-membrane domains; apical localization is observed in specific tissues and is phosphorylation-dependent. This polar PM subdomain is central to PIN1 directional function. Reason: A real and functionally important polar PM subdomain; kept as non-core because the polarity (apical versus basal) is tissue- and phosphorylation-dependent rather than a fixed property, while plasma membrane is the core location. Supporting Evidence: PMID:20407025 The apical-basal polar localization of the PIN proteins that determines the direction of auxin flow is controlled by reversible phosphorylation of the PIN hydrophilic loop
GO:0045177 apical part of cell	IDA PMID:33705718 AGC kinases and MAB4/MEL proteins maintain PIN polarity by l...	KEEP AS NON CORE	Summary: Reflects PIN1 apical polar localization. Correct but a broad cellular anatomical parent of apical plasma membrane. Reason: Consistent with polar localization; generic relative to apical plasma membrane. Retained as non-core. Supporting Evidence: PMID:20407025 Conversely, phosphomimic PIN1:GFP (Ser to Glu) showed apical localization in the shoot apex but did not rescue pin1 inflorescence defects.
GO:0005515 protein binding	IPI PMID:36226797 SUE4, a novel PIN1-interacting membrane protein, regulates a...	MARK AS OVER ANNOTATED	Summary: TAIR interaction with SUE4 (AT3G55880), a PIN1-interacting membrane protein that regulates acropetal auxin transport under sulfur deficiency. Generic protein binding term is uninformative. Reason: Biologically relevant interaction but GO:0005515 conveys no specific molecular function. Supporting Evidence: PMID:36226797 SUE4, a novel plasma membrane-localized protein, interacts with the polar auxin transporter PIN1
GO:0010168 ER body	IDA PMID:36398993 Mapping of the Classical Mutation rosette Highlights a Role ...	REMOVE	Summary: This annotation assigns PIN1 to an ER body. PMID:36398993 is a study of the tomato classical mutation rosette mapping to the BIG/UBR4 ortholog and the role of calcium in wound-induced rooting; the ER association it reports is for BIG, not for PIN1. PIN1 is a long PIN that resides at the plasma membrane, whereas only the short PINs (PIN5/PIN8) are ER-localized. There is no sound evidence that PIN1 is an ER-body resident protein. Reason: Appears to be a mis-assignment; the cited paper does not support PIN1 ER-body localization, and PIN1 is an established plasma-membrane protein. Supporting Evidence: PMID:35917925 The short PINs are typically found at the endoplasmic reticulum, whereas the long PINs are at the plasma membrane and dynamically regulated by endocytosis and recycling PMID:36398993 Subcellular localization of BIG suggests that, like its mammalian ortholog, it is associated with the endoplasmic reticulum.
GO:0048830 adventitious root development	IMP PMID:36398993 Mapping of the Classical Mutation rosette Highlights a Role ...	KEEP AS NON CORE	Summary: PIN1-dependent auxin transport is implicated in wound-induced (adventitious) rooting; in the cited study PIN1 accumulation was sensitive to calcium levels in ro/big mutants, linking PIN1-mediated transport to wound-induced root formation. This is a downstream developmental output of auxin transport. Reason: A pleiotropic downstream developmental process mediated via PIN1 auxin transport; evidence is indirect (a tomato BIG study). Retained as non-core. Supporting Evidence: PMID:36398993 accumulation of the auxin transporter PIN-FORMED1 (PIN1) was sensitive to calcium levels in the ro/big mutants
GO:0060918 auxin transport	IMP PMID:36398993 Mapping of the Classical Mutation rosette Highlights a Role ...	ACCEPT	Summary: Genetic and physiological evidence that PIN1 contributes to auxin transport (reduced transport rates and NPA hypersensitivity in the relevant mutants). Consistent with PIN1 core role in auxin transport. Reason: Core biological process, corroborated by the founding and structural studies. Supporting Evidence: PMID:36398993 ro mutants were severely inhibited in formation of wound-induced roots (WiRs) and had reduced auxin transport rates.
GO:0010262 somatic embryogenesis	IMP PMID:36345646 Endogenous auxin maintains embryonic cell identity and promo...	KEEP AS NON CORE	Summary: Endogenous auxin (transported by PINs including PIN1) maintains embryonic cell identity and promotes somatic embryo development. This is a downstream developmental process patterned by PIN1-generated auxin gradients. Reason: Pleiotropic developmental output acting via auxin transport; non-core. Supporting Evidence: PMID:36345646 polar auxin transport, with AUXIN/LIKE-AUX influx and PIN-FORMED1 efflux carriers as important drivers, is required for the transition of embryonic cells to proembryos
GO:0005737 cytoplasm	HDA PMID:15610358 High-throughput protein localization in Arabidopsis using Ag...	UNDECIDED	Summary: High-throughput GFP-fusion localization. PIN1 cycles between the plasma membrane and endosomal compartments via GNOM-dependent recycling, so a cytoplasmic/endosomal signal is expected for trafficking intermediates, but the plasma membrane is the functional site. Reason: The cited publication (PMID:15610358) is a generic high-throughput GFP-fusion localization methods paper; its available abstract does not mention PIN1 or report a cytoplasmic localization for PIN1 specifically, so it does not substantiate this GO:0005737 (cytoplasm) annotation. No verbatim PIN1-specific supporting passage could be extracted.
GO:0009506 plasmodesma	HDA PMID:21533090 Arabidopsis plasmodesmal proteome.	UNDECIDED	Summary: PIN1 was detected in a plasmodesmal proteome. Plasmodesmal plasma membrane is continuous with the cell-surface PM, so detection here is plausible for a PM protein but does not indicate a distinct functional plasmodesmal role. Reason: The cited publication (PMID:21533090) is the Arabidopsis plasmodesmal proteome paper, but its cached text does not mention PIN1 anywhere, so it does not substantiate plasmodesmal detection of PIN1 for this GO:0009506 (plasmodesma) annotation. No verbatim PIN1-specific supporting passage could be extracted.
GO:0005515 protein binding	IPI PMID:22715043 A PP6-type phosphatase holoenzyme directly regulates PIN pho...	MARK AS OVER ANNOTATED	Summary: UniProt interactions with FYPP1 (Q9LHE7) and FYPP3 (Q9SX52), subunits of a PP6-type phosphatase holoenzyme that dephosphorylates PIN1 and regulates auxin efflux. Generic protein binding term is uninformative. Reason: A real regulatory phosphatase interaction, but GO:0005515 conveys no specific molecular function. Supporting Evidence: PMID:22715043 FyPP1 and FyPP3 interact with a subset of PIN proteins and regulate PIN protein phosphorylation and targeting in vivo
GO:0010329 auxin efflux transmembrane transporter activity	IMP PMID:9856939 Regulation of polar auxin transport by AtPIN1 in Arabidopsis...	ACCEPT	Summary: The founding study identified AtPIN1 as a transmembrane component of the auxin efflux carrier; pin1 mutants have diminished polar auxin transport. This mutant-phenotype evidence supports the core efflux transporter function. Reason: Core molecular function, independently established here and later directly demonstrated structurally (PMID:35917925). Supporting Evidence: PMID:9856939 AtPIN1 may act as a transmembrane component of the auxin efflux carrier.
GO:0005515 protein binding	IPI PMID:17586653 Ubiquitin lysine 63 chain forming ligases regulate apical do...	MARK AS OVER ANNOTATED	Summary: UniProt interaction (Q9LY87) in the context of K63 ubiquitin chain ligases regulating apical dominance. Generic protein binding term is uninformative about molecular function. Reason: Interaction is recorded but GO:0005515 conveys no specific function. Supporting Evidence: PMID:17586653 RGLG2 and PIN1 can interact in the yeast two-hybrid system
GO:0009793 embryo development ending in seed dormancy	IMP PMID:20407025 Phosphorylation of conserved PIN motifs directs Arabidopsis ...	KEEP AS NON CORE	Summary: Loss-of-phosphorylation PIN1 internalizes during embryogenesis causing strong embryo defects, demonstrating a PIN1 requirement in embryo development through proper polar auxin transport. Reason: Important downstream developmental role mediated by PIN1 polar auxin transport; pleiotropic, non-core. Supporting Evidence: PMID:20407025 induced internalization of PIN1:GFP during embryogenesis, leading to strong embryo defects
GO:0005886 plasma membrane	IDA PMID:18337510 Auxin transport inhibitors impair vesicle motility and actin...	ACCEPT	Summary: TAIR IDA annotation of PIN1 plasma-membrane localization from PMID:18337510, a study of how auxin transport inhibitors affect actin-dependent vesicle trafficking. The cached record is abstract-only, so the supporting localization data cannot be inspected here. Reason: Plasma-membrane localization is unambiguously correct for PIN1 (accepted here on other experimental rows, e.g. PMID:33705718 and PMID:35917925). The cached record for PMID:18337510 is abstract-only; the curator read the full text, so an experimental IDA for a clearly correct localization is deferred to the curator rather than overruled from the abstract.
GO:0005886 plasma membrane	IDA PMID:19825598 Plasma membrane-associated SCAR complex subunits promote cor...	ACCEPT	Summary: TAIR IDA annotation of PIN1 plasma-membrane localization from PMID:19825598, whose abstract concerns plasma-membrane localization of the SCAR complex subunits BRK1 and SCAR1 and cortical F-actin. The cached record is abstract-only, so the PIN1 data the curator used cannot be inspected here. Reason: Plasma-membrane localization is unambiguously correct for PIN1 (accepted here on other experimental rows, e.g. PMID:33705718 and PMID:35917925). The cached record for PMID:19825598 is abstract-only; an abstract foregrounding SCAR-complex subunits does not establish that the full text did not also image PIN1, and the curator read the full text, so an experimental IDA for a clearly correct localization is deferred to the curator rather than overruled from the abstract.
GO:0005886 plasma membrane	IDA PMID:18539115 Differential expression of WOX genes mediates apical-basal a...	ACCEPT	Summary: TAIR IDA annotation of PIN1 plasma-membrane localization from PMID:18539115, a study of WOX gene expression in apical-basal axis formation whose abstract mentions PIN1 only as a reporter for auxin response. The cached record is abstract-only, so the supporting localization data cannot be inspected here. Reason: Plasma-membrane localization is unambiguously correct for PIN1 (accepted here on other experimental rows, e.g. PMID:33705718 and PMID:35917925). The cached record for PMID:18539115 is abstract-only; the curator read the full text, so an experimental IDA for a clearly correct localization is deferred to the curator rather than overruled from the abstract.
GO:0009505 plant-type cell wall	IDA PMID:18539115 Differential expression of WOX genes mediates apical-basal a...	MARK AS OVER ANNOTATED	Summary: PIN1 is an integral ten-pass plasma-membrane protein; assignment to the plant-type cell wall is not biologically meaningful for an auxin efflux carrier and likely reflects PM or apoplast-adjacent signal. Reason: Inconsistent with PIN1 being an integral membrane transporter; the cell wall is not a functional compartment for PIN1. Supporting Evidence: PMID:35917925 The transmembrane domain of PIN1 has ten transmembrane segments (TM1 to TM10), with both N and C termini located extracellularly
GO:0048825 cotyledon development	IGI PMID:15371311 PIN-FORMED1 and PINOID regulate boundary formation and cotyl...	KEEP AS NON CORE	Summary: PIN1 acts with PINOID to regulate boundary formation and cotyledon development during embryogenesis, via patterning of auxin distribution. Reason: Downstream developmental output of PIN1 auxin transport; pleiotropic, non-core. Supporting Evidence: PMID:15371311 Single mutations in the PIN-FORMED1 (PIN1) and PINOID (PID) genes, which mediate auxin-dependent organ formation, moderately disrupt the symmetric patterning of cotyledons
GO:0009908 flower development	IMP PMID:20407025 Phosphorylation of conserved PIN motifs directs Arabidopsis ...	KEEP AS NON CORE	Summary: PIN1-dependent polar auxin transport is required for flower formation at the shoot apex; defective PIN1 phosphorylation causes inflorescence and flower defects. pin1 mutants form pin-shaped naked inflorescences lacking flowers. Reason: Downstream developmental process patterned by PIN1 auxin transport; pleiotropic, non-core. Supporting Evidence: PMID:20407025 Loss-of-phosphorylation PIN1:green fluorescent protein (GFP) (Ser to Ala) induced inflorescence defects
GO:0010229 inflorescence development	IMP PMID:20407025 Phosphorylation of conserved PIN motifs directs Arabidopsis ...	KEEP AS NON CORE	Summary: PIN1 is required for normal inflorescence development; the defining pin1 phenotype is a naked, pin-shaped inflorescence resulting from failed organ initiation at the shoot apex. Reason: Downstream developmental output of PIN1 polar auxin transport; non-core. Supporting Evidence: PMID:20407025 Loss-of-phosphorylation PIN1:green fluorescent protein (GFP) (Ser to Ala) induced inflorescence defects file:ARATH/PIN1/PIN1-deep-research-falcon.md pin1 mutants exhibit severe organ initiation failures, producing “pin-like” stems with reduced or absent flowers/organs, supporting a causal link between PIN1-mediated PAT and organogenesis.
GO:0048826 cotyledon morphogenesis	IMP PMID:20407025 Phosphorylation of conserved PIN motifs directs Arabidopsis ...	KEEP AS NON CORE	Summary: PIN1-mediated auxin transport during embryogenesis shapes cotyledon formation; phosphorylation-deficient PIN1 produces embryo and cotyledon defects. Reason: Downstream developmental output of PIN1 auxin transport; non-core. Supporting Evidence: PMID:20407025 induced internalization of PIN1:GFP during embryogenesis, leading to strong embryo defects
GO:0010358 leaf shaping	IMP PMID:16971475 ASYMMETRIC LEAVES1 and auxin activities converge to repress ...	UNDECIDED	Summary: This annotation cites PMID:16971475 for a PIN1 role in leaf shaping, but that paper concerns AS1/KNOX (BREVIPEDICELLUS) interactions with auxin gradients in leaf development and does not mention PIN1 specifically. Reason: The cited publication (PMID:16971475) does not mention PIN1 in its available text; it addresses ASYMMETRIC LEAVES1/KNOX and generic auxin gradients in leaf development, so it does not substantiate this PIN1 (IMP) GO:0010358 (leaf shaping) annotation. No verbatim PIN1-specific supporting passage could be extracted.
GO:0010051 xylem and phloem pattern formation	IMP PMID:16943276 The HVE/CAND1 gene is required for the early patterning of l...	UNDECIDED	Summary: This annotation cites PMID:16943276 for a PIN1 role in xylem/phloem pattern formation, but that paper is about HVE/CAND1 and explicitly states its venation-patterning pathway does NOT involve PIN1, so the citation does not support a PIN1 function here. (PIN1-dependent auxin canalization in vascular patterning is a real concept but is not substantiated by this particular paper.) Reason: The cited publication (PMID:16943276) does not substantiate a PIN1 role; it states the HVE/CAND1 venation-patterning pathway acts in a pathway that involves AXR1 'but not LOP1, PIN1, CVP1 or CVP2'. The citation therefore does not support this PIN1 (IMP) GO:0010051 annotation, and no supporting PIN1 passage exists in the text.
GO:0009630 gravitropism	IMP PMID:16601150 PIN proteins perform a rate-limiting function in cellular au...	UNDECIDED	Summary: This annotation cites PMID:16601150 for a PIN1 role in gravitropism, but that paper establishes the rate-limiting auxin-efflux function of PINs in heterologous systems and does not address gravitropism or provide PIN1-specific gravitropic-phenotype evidence. Reason: The cited publication (PMID:16601150) demonstrates that PINs catalyze rate-limiting cellular auxin efflux but does not mention gravitropism; it does not substantiate this PIN1 (IMP) GO:0009630 (gravitropism) annotation. No verbatim supporting passage linking PIN1 to gravitropism could be extracted.
GO:0009640 photomorphogenesis	TAS PMID:16141452 Brassinosteroids stimulate plant tropisms through modulation...	UNDECIDED	Summary: This annotation cites PMID:16141452 for a PIN1 role in photomorphogenesis, but that paper examines brassinosteroid modulation of polar auxin transport and tropisms acting on the PIN2 protein; it does not provide PIN1-specific evidence for photomorphogenesis. Reason: The cited publication (PMID:16141452) describes brassinosteroid effects on polar auxin transport and tropisms mediated at the protein level by PIN2 (PIN genes are only noted as transcriptionally regulated); it does not substantiate a specific PIN1 role in photomorphogenesis (GO:0009640). No verbatim PIN1-specific supporting passage could be extracted.
GO:0009925 basal plasma membrane	IDA PMID:11959844 The Arabidopsis PILZ group genes encode tubulin-folding cofa...	KEEP AS NON CORE	Summary: PIN1 localizes to the basal plasma-membrane domain of vascular cells, the polar domain that directs basipetal (rootward) auxin flow. This basal polar domain is a defining feature of PIN1 in vascular tissue. Reason: A real, functionally important polar PM subdomain; kept as non-core because apical-versus-basal polarity is tissue- and phosphorylation-dependent while plasma membrane is the core location. Supporting Evidence: PMID:9856939 the AtPIN1 protein was detected at the basal end of auxin transport-competent cells in vascular tissue file:ARATH/PIN1/PIN1-deep-research-falcon.md In vascular tissues and the root stele, PIN1 is frequently described as
GO:0009926 auxin polar transport	IMP PMID:16601150 PIN proteins perform a rate-limiting function in cellular au...	ACCEPT	Summary: PIN proteins, including PIN1, perform the rate-limiting step of cellular auxin efflux that underlies directional polar auxin transport. This is a core biological process for PIN1. Reason: Core biological process; PIN1 polarity dictates the direction of polar auxin transport. Supporting Evidence: PMID:16601150 PINs mediate auxin efflux from mammalian and yeast cells without needing additional plant-specific factors PMID:9856939 Mutations affecting the PIN-FORMED (PIN1) gene diminish polar auxin transport in Arabidopsis thaliana inflorescence axes. file:ARATH/PIN1/PIN1-deep-research-falcon.md which determines the direction of auxin flow between neighboring cells.
GO:0045177 apical part of cell	IDA PMID:16107478 The gene ENHANCER OF PINOID controls cotyledon development i...	KEEP AS NON CORE	Summary: PIN1 apical polar localization observed during cotyledon and embryo development. Correct but a broad anatomical parent of apical plasma membrane. Reason: Consistent with PIN1 polar localization; generic relative to apical plasma membrane. Retained as non-core. Supporting Evidence: PMID:16107478 reversal of polarity of the PIN1 auxin transport facilitator in the apex is only occasional
GO:0048364 root development	IMP PMID:9856939 Regulation of polar auxin transport by AtPIN1 in Arabidopsis...	KEEP AS NON CORE	Summary: PIN1-mediated polar auxin transport is required for normal root system development; pin1 mutants show broad organ-formation defects. Reason: Downstream developmental output of PIN1 auxin transport; non-core. Supporting Evidence: PMID:9856939 abnormalities in the number, size, shape, and position of lateral organs
GO:0048367 shoot system development	IMP PMID:11060241 PIN-FORMED 1 regulates cell fate at the periphery of the sho...	KEEP AS NON CORE	Summary: PIN1 regulates cell fate at the periphery of the shoot apical meristem, controlling organ initiation and overall shoot system development. Reason: Downstream developmental output of PIN1 polar auxin transport; non-core. Supporting Evidence: PMID:11060241 Loss of function severely affects organ initiation, and pin1 mutants are characterised by an inflorescence meristem that does not initiate any flowers

Gene Description

Existing Annotations Review

Core Functions

Plasma-membrane auxin efflux transmembrane transporter that binds indolic auxins (notably IAA) in an intracellular pocket and exports them out of the cell; activity is enhanced by AGC-kinase (D6PK) phosphorylation and inhibited by NPA. PIN1 adopts a 10-TM NhaA fold and functions as a homodimer.

By localizing asymmetrically (apical or basal) within the plasma membrane, PIN1 sets the direction of intercellular (polar) auxin transport, performing the rate-limiting cellular efflux step that establishes the auxin gradients and maxima patterning plant development.

Self-associates into a homodimer at the plasma membrane; the dimer (TM1/TM2/TM7 interface) is the assembled form observed in the cryo-EM structure.

References

Deep Research

Falcon

📚 Additional Documentation

Notes

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