Multiactivity mechanisms contributing to polar auxin transport

Cell-to-cell auxin transport arises from the spatial arrangement and regulation of membrane uptake and export activities. This module represents experimentally grounded land-plant transport combinations: complementary influx/efflux, pair-specific PIN–ABCB cooperation, and carrier activation by kinases or TWD1. Each named mechanism contains at least two substantive activities and native-context evidence; satisfying it identifies a supported mechanistic combination, not sufficiency to generate tissue polarity or a complete transport network. Carrier-mediated uptake is context-dependent because protonated IAA can also enter by diffusion. Native polarity and tissue flow are distinguished from cellular or heterologous export. Arabidopsis provides the characterized multiactivity mechanisms. Rice contributes only an optional sampled influx/efflux segment, and moss/liverwort PINs are exporter comparators; neither alone certifies an equivalent native mechanism. Nuclear signaling, biosynthesis, intracellular short-PIN/PILS compartmentation, general vesicle trafficking and bulk phloem transport are outside the modeled boundary.

MODULE:auxin_polar_transportCOMPLETECONCRETEBiological Processmodules/auxin_polar_transport.yaml

auxin polar transportGO:0009926

url:https://www.jstage.jst.go.jp/article/plmorphol/36/1/36_3/_html/-char/en

Distinguishes cell-to-environment, non-canalized intercellular and canalized auxin transport; exporter biochemistry and tissue-level directionality require separate evidence.

“cell-to-environment auxin transport”, “non-canalized intercellular auxin transport”, and “canalized auxin transport”.

PMID:36786017

Functional validation of predicted orthologs is needed to establish conserved biochemical properties and biological roles.

more functional validations of the predicted extant orthologs are required to confirm the conservation of the biochemical properties

PMID:42618840

Review supports compartmental and cooperative transport framing; its broad ABCB efflux wording is qualified here by primary ABCB4 bidirectionality evidence.

Although ABCBs can mediate auxin efflux independently, their interaction with PIN proteins enhances transport efficiency and directionality.

PMID:38211951

Abstract-level review establishes transporter biochemical/structural diversity; individual mechanisms here are anchored to primary experiments.

transported by a diverse range of transporters with distinct biochemical and structural properties.

PMID:36608348

Abstract-level review supports integrating spatial models with experiments; model predictions are not recast as direct flux measurements.

how auxin movement between cells regulates development at the tissular scale.

PMID:39931795

Abstract-level review distinguishes post-translational effects on transporter activity, localization and specificity.

activation status, localization and substrate specificity.

PMID:40100293

ABCB functions extend beyond auxin transport, consistent with avoiding auxin-only family scope.

PMID:31712756

An early streptophyte PIN exporter supports ancestral cellular transport, not conservation of an entire multicellular directional circuit.

PMID:42271607

Tested non-plant PIN-like proteins did not support directional export in heterologous systems despite structural resemblance; this is not a universal absence claim for all algae.

PMID:16601151

Native PIN polarity contributes to the direction of auxin flow.

PMID:16601150

PIN cellular export can be distinguished from PGP/ABCB transport; universal ABCB dependence is not inferred.

PMID:33705718

Kinase/MAB4-dependent restriction of PIN lateral diffusion supports polarity maintenance; PID/WAG can localize apolarly.

PMID:38513023

ABCB19 directly transports brassinosteroids; cellular IAA-export evidence must be distinguished from the isolated proteoliposome assay.

PMID:40720658

AUX1 structural and cellular evidence supports a proton-coupled import mechanism, without specifying an unmeasured fixed stoichiometry.

PMID:42130089

Comparative review distinguishes local PIN-mediated gradients and moss symplastic branching models from long-range PIN-mediated transport in vascular plants; no blanket bryophyte polarity is inferred.

branching is regulated mainly by symplastic auxin diffusion through plasmodesmata

PMID:41984944

Native early growing moss phyllids show apolar PINA/PINB and a role in reducing intracellular auxin; older polar tip localization is stage-dependent and does not establish a universal leaf-wide directional stream.

moss PIN transporters do not participate in polar auxin transport during phyllid development but mainly reduce intracellular auxin concentration.

PMID:41061699

A physics-based native moss branching study supports symplasmic diffusion as a sufficient model for observed branch patterns; its cache is abstract-only, so detailed parameters are not asserted.

PMID:32699109

Direct ABCB1 activation by TWD1 provides transporter-regulator evidence without requiring a settled PPIase mechanism.

Provider Falcon/fallback attempts failed; primary and review-source retrieval and access limits are documented in adjacent notes. Canonical cited publication caches were not hand-edited. The rice pairing is an explicitly limited synthesis of native functions, not a measured physical complex or complete reconstruction.

30Nodes

21Parts

2Variant Sets

8Variants

20Annotons

7Connections

Derived QC

Recommended-field compliance

100.0% recommended fields populated

All recommended fields populated.

Module deep research

✗ none found

No MODULE:auxin_polar_transport deep-research report alongside the module YAML.

Leaf nodes lacking representative members

✓ every leaf node grounds to a representative protein.

Template conformance

✓ every declared conforms_to bundle matches its template motif.

Function consistency and core coverage

20 gene-function check(s) reflected in core functions · 0 conflict(s) · 20 evidence or coverage gap(s) (40 comparison(s))

Retained noncore functions are reported separately; they do not require promotion to core functions. Support from representative genes does not establish conservation across the whole family. Missing reviews or identifiers leave a claim unverified.

Annoton	Participant	Function	Assessment
osaux1_influx	OsAUX1 UniProtKB:Q5N892 Gene	auxin influx transmembrane transporter activity GO:0010328	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
ospin2_efflux	PIN2 UniProtKB:Q651V6 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
abcb4_uptake_activity	ABCB4 UniProtKB:O80725 Gene	auxin influx transmembrane transporter activity GO:0010328	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
abcb4_export_activity	ABCB4 UniProtKB:O80725 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
npf63_auxin_influx	NRT1.1 UniProtKB:Q05085 Gene	auxin influx transmembrane transporter activity GO:0010328	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pina_comparator_efflux	PINA UniProtKB:Q5TK28 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pinb_comparator_efflux	PINB UniProtKB:A9RN82 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
mppin1_comparator_efflux	MpPIN1 UniProtKB:A0A2R6WHW5 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
aux1_influx	AUX1 UniProtKB:Q96247 Gene	auxin influx transmembrane transporter activity GO:0010328	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pin2_efflux	PIN2 UniProtKB:Q9LU77 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pin3_emergence_efflux	PIN3 UniProtKB:Q9S7Z8 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
lax3_influx	LAX3 UniProtKB:Q9CA25 Gene	auxin influx transmembrane transporter activity GO:0010328	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
abcb19_auxin_export	ABCB19 UniProtKB:Q9LJX0 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pin1_efflux	PIN1 UniProtKB:Q9C6B8 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
d6pk_pin_activation	D6PK UniProtKB:Q9FG74 Gene	protein serine/threonine kinase activity GO:0004674	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
d6pk_pin3_efflux	PIN3 UniProtKB:Q9S7Z8 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pid_pin_activation	PID UniProtKB:O64682 Gene	protein serine/threonine kinase activity GO:0004674	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pid_pin1_efflux	PIN1 UniProtKB:Q9C6B8 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
twd1_abcb1_regulator	FKBP42 UniProtKB:Q9LDC0 Gene	transporter activator activity GO:0141109	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
abcb1_twd1_efflux	ABCB1 UniProtKB:Q9ZR72 Gene	auxin efflux transmembrane transporter activity GO:0010329	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
osaux1_influx	OsAUX1 classification PANTHER:PTHR48017 Family	auxin influx transmembrane transporter activity GO:0010328	Family Review Missing No supported structured family review is available for PANTHER:PTHR48017.
ospin2_efflux	PIN2 classification PANTHER:PTHR31752:SF4 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR31752:SF4.
abcb4_uptake_activity	ABCB4 classification PANTHER:PTHR43394:SF16 Family	auxin influx transmembrane transporter activity GO:0010328	Family Review Missing No supported structured family review is available for PANTHER:PTHR43394:SF16.
abcb4_export_activity	ABCB4 classification PANTHER:PTHR43394:SF16 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR43394:SF16.
npf63_auxin_influx	NRT1.1 (NPF6.3) classification PANTHER:PTHR11654 Family	auxin influx transmembrane transporter activity GO:0010328	Family Function Unreviewed The family review has no applicable adjudication supporting or excluding GO:0010328.
pina_comparator_efflux	PINA classification PANTHER:PTHR31752:SF18 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR31752:SF18.
pinb_comparator_efflux	PINB classification PANTHER:PTHR31752:SF18 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR31752:SF18.
mppin1_comparator_efflux	MpPIN1 classification PANTHER:PTHR31752:SF18 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR31752:SF18.
aux1_influx	AUX1 classification PANTHER:PTHR48017 Family	auxin influx transmembrane transporter activity GO:0010328	Family Review Missing No supported structured family review is available for PANTHER:PTHR48017.
pin2_efflux	PIN2 classification PANTHER:PTHR31752:SF4 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR31752:SF4.
pin3_emergence_efflux	PIN3 classification PANTHER:PTHR31752:SF60 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR31752:SF60.
lax3_influx	LAX3 classification PANTHER:PTHR48017 Family	auxin influx transmembrane transporter activity GO:0010328	Family Review Missing No supported structured family review is available for PANTHER:PTHR48017.
abcb19_auxin_export	ABCB19 classification PANTHER:PTHR43394:SF11 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR43394:SF11.
pin1_efflux	PIN1 classification PANTHER:PTHR31752:SF18 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR31752:SF18.
d6pk_pin_activation	D6PK classification PANTHER:PTHR45637 Family	protein serine/threonine kinase activity GO:0004674	Family Review Missing No supported structured family review is available for PANTHER:PTHR45637.
d6pk_pin3_efflux	PIN3 classification PANTHER:PTHR31752:SF60 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR31752:SF60.
pid_pin_activation	PID classification PANTHER:PTHR45637 Family	protein serine/threonine kinase activity GO:0004674	Family Review Missing No supported structured family review is available for PANTHER:PTHR45637.
pid_pin1_efflux	PIN1 classification PANTHER:PTHR31752:SF18 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR31752:SF18.
twd1_abcb1_regulator	FKBP42 classification PANTHER:PTHR11242:SF0 Family	transporter activator activity GO:0141109	Family Review Missing No supported structured family review is available for PANTHER:PTHR11242:SF0.
abcb1_twd1_efflux	ABCB1 classification PANTHER:PTHR43394:SF11 Family	auxin efflux transmembrane transporter activity GO:0010329	Family Review Missing No supported structured family review is available for PANTHER:PTHR43394:SF11.

Gene-review completeness (17/17 grounded genes reviewed)

3 complete review(s) · 3 with deep research · 0 missing review · 14 reviewed but lacking deep research

Gene	Review	Complete	Deep research
ABCB1 Q9ZR72	✓	69/72	✗
ABCB19 Q9LJX0	✓	71/73	✗
ABCB4 O80725	✓	✓	✗
AUX1 Q96247	✓	21/23	✓
D6PK Q9FG74	✓	38/40	✗
FKBP42 Q9LDC0	✓	27/29	✗
LAX3 Q9CA25	✓	10/12	✗
MpPIN1 A0A2R6WHW5	✓	✓	✗
NRT1.1 Q05085	✓	✓	✓
OsAUX1 Q5N892	✓	3/5	✗
PID O64682	✓	41/43	✗
PIN1 Q9C6B8	✓	44/45	✓
PIN2 Q651V6	✓	11/12	✗
PIN2 Q9LU77	✓	33/34	✗
PIN3 Q9S7Z8	✓	30/32	✗
PINA Q5TK28	✓	4/5	✗
PINB A9RN82	✓	4/5	✗

Tree

Native-context multiactivity mechanisms contributing to polar auxin transportBiological Processauxin_polar_transport

Parts
1. Sampled rice influx and efflux capacities; not a demonstrated coupled route optional
2. Rice sampled complementary influx/efflux segmentBiological Processrice_sampled_influx_efflux
  
  Parts
  1. 1. OsAUX1-mediated auxin uptake
  2. OsAUX1-mediated auxin uptakeTransport Steprice_auxin_influx
    
    Annotons
    
    OsAUX1: auxin influx transmembrane transporter activity Gene Product: OsAUX1
  3. 2. Rice PIN2-mediated auxin export
  4. Rice PIN2-mediated auxin exportTransport Steprice_pin2_export
    
    Annotons
    
    PIN2: auxin efflux transmembrane transporter activity Gene Product: PIN2
3. 1. Concentration-dependent ABCB4 branch optional
4. Conditional ABCB4 import/exportTransport Stepconditional_abcb4
  
  Variants
  1. abcb4_direction_states by Substrate concentration and assay/cell context (One Or More)
    
    ABCB4 conditional uptakeTransport Stepabcb4_uptake
    
    Annotons
    
    ABCB4: auxin influx transmembrane transporter activity Gene Product: ABCB4
    
    ABCB4 conditional exportTransport Stepabcb4_export
    
    Annotons
    
    ABCB4: auxin efflux transmembrane transporter activity Gene Product: ABCB4
5. 2. Nutrient-conditioned alternative influx optional
6. NRT1.1 (NPF6.3) nitrate-conditioned auxin uptakeTransport Stepnitrate_conditioned_auxin_uptake
  
  Annotons
  - NRT1.1: auxin influx transmembrane transporter activity Gene Product: NRT1.1
7. 3. Native bryophyte exporter comparison optional
8. Bryophyte exporter activities and native contextModulebryophyte_exporter_comparators
  
  Parts
  1. Taxon-specific exporter comparator optional
  2. PINA exporter comparatorTransport Stepphypa_pina_comparator
    
    Annotons
    
    PINA: auxin efflux transmembrane transporter activity Gene Product: PINA
  3. Taxon-specific exporter comparator optional
  4. PINB exporter comparatorTransport Stepphypa_pinb_comparator
    
    Annotons
    
    PINB: auxin efflux transmembrane transporter activity Gene Product: PINB
  5. Taxon-specific exporter comparator optional
  6. MpPIN1 exporter comparatorTransport Stepmarpo_mppin1_comparator
    
    Annotons
    
    MpPIN1: auxin efflux transmembrane transporter activity Gene Product: MpPIN1
Variants
1. Experimentally grounded native-context transport mechanisms by Arabidopsis tissue and mechanistic pairing (One Or More)
  1. Arabidopsis root-tip to elongation-zone transportBiological Processarabidopsis_root_outer_stream
    
    Parts
    
    1. AUX1-mediated uptake in the root outer tissues
    
    AUX1-mediated uptake in the root outer tissuesTransport Stepauxin_influx
    
    Annotons
    
    AUX1: auxin influx transmembrane transporter activity Gene Product: AUX1
    
    2. PIN2-mediated root outer-tissue efflux
    
    PIN2-mediated root outer-tissue effluxTransport Steppin_polar_efflux
    
    Annotons
    
    PIN2: auxin efflux transmembrane transporter activity Gene Product: PIN2
  2. Arabidopsis sequential PIN3/LAX3 transport during emergenceBiological Processarabidopsis_lateral_root_emergence
    
    Parts
    
    1. PIN3 export shaping the cortical auxin field
    
    PIN3 export shaping the cortical auxin fieldTransport Steppin3_emergence_export
    
    Annotons
    
    PIN3: auxin efflux transmembrane transporter activity Gene Product: PIN3
    
    2. LAX3 uptake in selected overlying cell files
    
    LAX3 uptake in selected overlying cell filesTransport Steplax3_emergence_import
    
    Annotons
    
    LAX3: auxin influx transmembrane transporter activity Gene Product: LAX3
  3. Arabidopsis PIN1–ABCB19 coordinated exportBiological Processarabidopsis_pin1_abcb19_cooperation
    
    Parts
    
    1. ABCB19 transport and PIN1 membrane stabilization
    
    ABCB19 transport and PIN1 membrane stabilizationTransport Stepabcb_auxin_export
    
    Annotons
    
    ABCB19: auxin efflux transmembrane transporter activity Gene Product: ABCB19
    
    2. PIN1 export in overlapping membrane domains
    
    PIN1 export in overlapping membrane domainsTransport Steppin1_cooperative_export
    
    Annotons
    
    PIN1: auxin efflux transmembrane transporter activity Gene Product: PIN1
  4. Arabidopsis D6PK-regulated PIN3 exportBiological Processarabidopsis_d6pk_pin3
    
    Parts
    
    1. D6PK kinase activation
    
    D6PK kinase activationRegulatory Stepd6pk_pin_regulation
    
    Annotons
    
    D6PK: protein serine/threonine kinase activity Gene Product: D6PK
    
    2. PIN3 efflux regulated by D6PK
    
    PIN3 efflux regulated by D6PKTransport Stepd6pk_pin3_export
    
    Annotons
    
    PIN3: auxin efflux transmembrane transporter activity Gene Product: PIN3
  5. Arabidopsis PID-regulated PIN1 exportBiological Processarabidopsis_pid_pin1
    
    Parts
    
    1. PID kinase activation
    
    PID kinase activationRegulatory Steppid_pin_regulation
    
    Annotons
    
    PID: protein serine/threonine kinase activity Gene Product: PID
    
    2. PIN1 efflux regulated by PID
    
    PIN1 efflux regulated by PIDTransport Steppid_pin1_export
    
    Annotons
    
    PIN1: auxin efflux transmembrane transporter activity Gene Product: PIN1
  6. Arabidopsis TWD1-regulated ABCB1 transportBiological Processarabidopsis_twd1_abcb1
    
    Parts
    
    1. TWD1 activation of ABCB1
    
    TWD1 activation of ABCB1Regulatory Steptwd1_abcb1_activation
    
    Annotons
    
    FKBP42: transporter activator activity Gene Product: FKBP42
    
    2. ABCB1 export in the TWD1-regulated context
    
    ABCB1 export in the TWD1-regulated contextTransport Stepabcb1_twd1_dependent_export
    
    Annotons
    
    ABCB1: auxin efflux transmembrane transporter activity Gene Product: ABCB1

Details

Context

land plantsNCBITaxon:3193

Cellular exporter activity predates this sampled tissue-network boundary. The taxon envelope is not an evolutionary origin assertion or a negative claim about algal transport.

Native-context multiactivity mechanisms contributing to polar auxin transportBiological Processauxin_polar_transport

auxin polar transportGO:0009926

Context

land plantsNCBITaxon:3193

Cellular exporter activity predates this sampled tissue-network boundary. The taxon envelope is not an evolutionary origin assertion or a negative claim about algal transport.

All selectors identify exact products. PANTHER descriptors document verified membership only, with official names; they do not transfer a substrate, PM polarity or partner-specific effect throughout a broad family. Optional rice capacities, carrier branches and bryophyte comparators do not satisfy the root. Root satisfiability indicates a represented mechanism in its stated native context, not that the proteins alone reconstruct polarized tissue flow. No corpus module_ref targeted the prior internal node IDs; legacy root identity is preserved. No GO-CAM association is invented.

Part: Sampled rice influx and efflux capacities; not a demonstrated coupled route (optional)

Rice sampled complementary influx/efflux segmentBiological Processrice_sampled_influx_efflux

Two native transport capacities are sampled, but these independent studies do not establish a coupled native OsAUX1–PIN2 implementation. This optional segment cannot satisfy the parent polar-transport mechanism module.

Context

Oryza sativa Japonica GroupNCBITaxon:39947

Rice root auxin-distribution functions sampled by separate OsAUX1 and PIN2 studies

Connections

rice_auxin_influx -> rice_pin2_export Provides Input For

Mechanistic synthesis: influx and efflux connect through cellular IAA pools in a native rice transport segment. These studies do not directly assay an OsAUX1–PIN2 pair, prove every cell coexpresses them, or reconstruct a full ABCB/kinase circuit.

PMID:29650967

Native OsAUX1 root distribution phenotypes provide the influx side of this sampled segment; rice PIN2 evidence is separately anchored to PMID:29294052.

Part 1: OsAUX1-mediated auxin uptake

OsAUX1-mediated auxin uptakeTransport Steprice_auxin_influx

Annotons

OsAUX1: auxin influx transmembrane transporter activity

osaux1_influx

Participant: Gene Product: OsAUX1

Gene Product:

OsAUX1UniProtKB:Q5N892

Family:

OsAUX1 classificationPANTHER:PTHR48017 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: OsAUX1UniProtKB:Q5N892

Taxon:

Oryza sativa Japonica GroupNCBITaxon:39947

Function

auxin influx transmembrane transporter activityGO:0010328

Processes

auxin import into cellGO:0060919

Locations

plasma membraneGO:0005886

The Os01g63770 locus supports native rice auxin-influx physiology and complements Arabidopsis aux1; no purified/oocyte rice-carrier transport measurement is implied.

PMID:29650967

Locus-specific complementation and independent native rice T-DNA alleles support OsAUX1 function in root auxin distribution.

Part 2: Rice PIN2-mediated auxin export

Rice PIN2-mediated auxin exportTransport Steprice_pin2_export

Annotons

PIN2: auxin efflux transmembrane transporter activity

ospin2_efflux

Participant: Gene Product: PIN2

Gene Product:

PIN2UniProtKB:Q651V6

Family:

PIN2 classificationPANTHER:PTHR31752:SF4 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: PIN2UniProtKB:Q651V6

Taxon:

Oryza sativa Japonica GroupNCBITaxon:39947

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

Native rice PIN2 localizes at opposite PM faces in epidermal and cortical root cells; native mutants and cross-species complementation support the exporter function.

PMID:29294052

Native lra1 mapping, complementation and specific immunostaining identify rice PIN2 and its polar PM localization.

Part 1: Concentration-dependent ABCB4 branch (optional)

Conditional ABCB4 import/exportTransport Stepconditional_abcb4

Context-dependent carrier states; neither state alone supplies a complete multi-activity module.

Variant set: abcb4_direction_states by Substrate concentration and assay/cell context (One Or More)

ABCB4 conditional uptakeTransport Stepabcb4_uptake

Context

Arabidopsis thalianaNCBITaxon:3702

Low-IAA uptake conditions

Annotons

ABCB4: auxin influx transmembrane transporter activity

abcb4_uptake_activity

Participant: Gene Product: ABCB4

Gene Product:

ABCB4UniProtKB:O80725

Family:

ABCB4 classificationPANTHER:PTHR43394:SF16 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: ABCB4UniProtKB:O80725

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin influx transmembrane transporter activityGO:0010328

Processes

auxin import into cellGO:0060919

Locations

plasma membraneGO:0005886

ABCB4 direction depends on substrate concentration and assay/cell context. Root shootward transport direction must not be confused with the sign of transport across an individual cell membrane.

PMID:21992190

ABCB4 shows uptake at low IAA and conversion to efflux at a threshold in heterologous kinetics, alongside native context-dependent uptake/export evidence.

uptake converted to efflux at threshold indole-3-acetic acid (IAA) concentrations.

ABCB4 conditional exportTransport Stepabcb4_export

Context

Arabidopsis thalianaNCBITaxon:3702

IAA concentrations/cellular contexts supporting efflux

Annotons

ABCB4: auxin efflux transmembrane transporter activity

abcb4_export_activity

Participant: Gene Product: ABCB4

Gene Product:

ABCB4UniProtKB:O80725

Family:

Representative Members: ABCB4UniProtKB:O80725

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

ABCB4 direction depends on substrate concentration and assay/cell context. Root shootward transport direction must not be confused with the sign of transport across an individual cell membrane.

PMID:21992190

ABCB4 shows uptake at low IAA and conversion to efflux at a threshold in heterologous kinetics, alongside native context-dependent uptake/export evidence.

Part 2: Nutrient-conditioned alternative influx (optional)

NRT1.1 (NPF6.3) nitrate-conditioned auxin uptakeTransport Stepnitrate_conditioned_auxin_uptake

Context

Arabidopsis thalianaNCBITaxon:3702

Nitrate-dependent lateral-root auxin distribution; uptake inhibited by nitrate

PMID:31431511

NRT1.1 phosphorylation-dependent dynamics connect native auxin flux and nitrate signaling; the mechanism is condition-dependent.

Annotons

NRT1.1: auxin influx transmembrane transporter activity

npf63_auxin_influx

Participant: Gene Product: NRT1.1

Gene Product:

NRT1.1UniProtKB:Q05085

Family:

NRT1.1 (NPF6.3) classificationPANTHER:PTHR11654 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: NRT1.1UniProtKB:Q05085

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin influx transmembrane transporter activityGO:0010328

Processes

auxin import into cellGO:0060919

Locations

plasma membraneGO:0005886

NRT1.1/NPF6.3 also transports nitrate. Nitrate inhibits its auxin uptake; low-nitrate native lateral-root phenotypes do not make it a universal root influx component.

PMID:20627075

NRT1.1 facilitates auxin uptake and nitrate inhibits that activity; native low-nitrate effects link this transporter to lateral-root auxin distribution.

nitrate inhibits NRT1.1-dependent auxin uptake

Part 3: Native bryophyte exporter comparison (optional)

Bryophyte exporter activities and native contextModulebryophyte_exporter_comparators

These independent comparator activities broaden the evidence for PIN exporter biology. Their presence, alone or together, does not establish a complete multi-activity circuit or its kinase/ABCB dependencies.

Part: Taxon-specific exporter comparator (optional)

PINA exporter comparatorTransport Stepphypa_pina_comparator

Native-promoter PINA is polar at filament tips and changes localization across leaf stages. The 2026 native phyllid study finds apolar PINA/PINB in early growing organs, with older (bi)polar patterns confined to differentiated tips. H3-IAA export from induced PINA-GFP moss lines measures cellular export, not by itself canalized tissue flux.

Context

Physcomitrium patensNCBITaxon:3218

Comparative exporter evidence, not a completeness witness for the multi-activity module

Annotons

PINA: auxin efflux transmembrane transporter activity

pina_comparator_efflux

Participant: Gene Product: PINA

Gene Product:

PINAUniProtKB:Q5TK28

Family:

PINA classificationPANTHER:PTHR31752:SF18 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: PINAUniProtKB:Q5TK28

Taxon:

Physcomitrium patensNCBITaxon:3218

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

PMID:37528584

PINA-GFP increases H3-IAA export in moss and its native-promoter localization is tissue-dependent; no complete AUX1/ABCB/AGC circuit is inferred.

Part: Taxon-specific exporter comparator (optional)

PINB exporter comparatorTransport Stepphypa_pinb_comparator

Native PINA/PINB genetic redundancy and family-level heterologous export evidence support a PINB exporter inference; an individually identified PINB transport construct is not assumed from collective PpPINA–C labeling. Native-promoter PINB-GFP in the 2024 study is more evenly PM-distributed with an unidentified intracellular pool; its H3-IAA assay did not test PINB.

Context

Physcomitrium patensNCBITaxon:3218

Comparative exporter evidence, not a completeness witness for the multi-activity module

PMID:25448003

Native PINA/PINB disruptants identify partly redundant developmental contributions.

PMID:37528584

Native-promoter PINB localization differs from older overexpression polarity and does not identify its intracellular pool as ER.

PpPINB-GFP did not show visible polarity at the tip of protonema

Annotons

PINB: auxin efflux transmembrane transporter activity

pinb_comparator_efflux

Participant: Gene Product: PINB

Gene Product:

PINBUniProtKB:A9RN82

Family:

PINB classificationPANTHER:PTHR31752:SF18 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: PINBUniProtKB:A9RN82

Taxon:

Physcomitrium patensNCBITaxon:3218

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

PMID:25448004

Primary transporter and native-context evidence supports this exact bryophyte exemplar, without establishing an entire AUX1/ABCB/AGC-kinase network.

Part: Taxon-specific exporter comparator (optional)

MpPIN1 exporter comparatorTransport Stepmarpo_mppin1_comparator

MpPINZ-GFP H3-IAA export was measured in a moss host. Exact clone/genome sequence identity links that construct to MpPIN1. Native Marchantia rescue and tissue-specific polarity are separately documented by PMID:36880411; polarity is not universal across tissues.

Context

Marchantia polymorphaNCBITaxon:3197

Comparative exporter evidence, not a completeness witness for the multi-activity module

PMID:36880411

Native Marchantia CRISPR/rescue and localization support MpPIN1 contributions to dorsiventral patterning and gametangiophore tropisms; other tropisms persist.

Annotons

MpPIN1: auxin efflux transmembrane transporter activity

mppin1_comparator_efflux

Participant: Gene Product: MpPIN1

Gene Product:

MpPIN1UniProtKB:A0A2R6WHW5

Family:

MpPIN1 classificationPANTHER:PTHR31752:SF18 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: MpPIN1UniProtKB:A0A2R6WHW5

Taxon:

Marchantia polymorphaNCBITaxon:3197

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

PMID:37528584

MpPINZ-GFP increases H3-IAA export in a moss host; Marchantia localization and native physiology are separately qualified.

Variant set: Experimentally grounded native-context transport mechanisms by Arabidopsis tissue and mechanistic pairing (One Or More)

Alternatives encode particular two-activity implementations, not a universal AND of all carriers and regulators. Presence of a molecular pair alone does not guarantee tissue polarity or coexpression; the stated native context remains essential.

Arabidopsis root-tip to elongation-zone transportBiological Processarabidopsis_root_outer_stream

A native Arabidopsis transport implementation requiring two complementary carrier activities in the specified tissues. Passive entry and alternative carriers outside this route remain possible.

Context

Arabidopsis thalianaNCBITaxon:3702

Lateral root cap and elongating epidermis during the gravitropic response

PMID:20562236

Native PIN2 polarity differs between epidermis/lateral root cap and meristematic cortex; cortical rootward polarity contributes to gravitropism.

Connections

auxin_influx -> pin_polar_efflux Provides Input For

AUX1 uptake supplies the intracellular IAA pool from which PIN2 exports in a multicellular root stream. This is material continuity, not a physical AUX1–PIN2 complex or a universal uptake requirement.

PMID:16244669

Tissue-specific AUX1 expression and root transport modeling support the lateral-root-cap/epidermal path for the gravitropic auxin signal.

Part 1: AUX1-mediated uptake in the root outer tissues

AUX1-mediated uptake in the root outer tissuesTransport Stepauxin_influx

Annotons

AUX1: auxin influx transmembrane transporter activity

aux1_influx

Participant: Gene Product: AUX1

Gene Product:

AUX1UniProtKB:Q96247

Family:

AUX1 classificationPANTHER:PTHR48017 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: AUX1UniProtKB:Q96247

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin influx transmembrane transporter activityGO:0010328

Processes

auxin import into cellGO:0060919

Locations

plasma membraneGO:0005886

Supplies cellular IAA in the lateral root cap and elongating epidermis; proton coupling is supported without asserting an integer H+:IAA ratio.

PMID:16677815

AUX1 expression in Xenopus oocytes supports saturable pH-dependent IAA uptake.

Part 2: PIN2-mediated root outer-tissue efflux

PIN2-mediated root outer-tissue effluxTransport Steppin_polar_efflux

Annotons

PIN2: auxin efflux transmembrane transporter activity

pin2_efflux

Participant: Gene Product: PIN2

Gene Product:

PIN2UniProtKB:Q9LU77

Family:

Representative Members: PIN2UniProtKB:Q9LU77

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

PIN2 supports shootward flow in epidermis and lateral root cap; its young-cortex pool is rootward, so location is recorded as PM with tissue-specific polarity in prose.

PMID:9844024

AGR1/PIN2 promotes radiolabeled IAA efflux in a heterologous yeast assay; native mutants link this carrier to gravitropism.

Arabidopsis sequential PIN3/LAX3 transport during emergenceBiological Processarabidopsis_lateral_root_emergence

A spatially organized efflux/influx route during lateral-root emergence. Expression feedback through nuclear auxin signaling is contextual and outside this transport module.

Context

Arabidopsis thalianaNCBITaxon:3702

Cortical tissues overlying a developing lateral-root primordium

Connections

pin3_emergence_export -> lax3_emergence_import Provides Input For

PIN3-dependent auxin redistribution provides the extracellular signal/substrate pattern for later LAX3 uptake in selected neighboring cell files. The source combines modeling and native experiments; it does not establish pairwise carrier binding.

PMID:24150423

Sequential PIN3 then LAX3 induction was predicted by a spatial transport model and supported experimentally, stabilizing restricted LAX3 expression over the primordium.

PIN3 and LAX3 must be induced consecutively

Part 1: PIN3 export shaping the cortical auxin field

PIN3 export shaping the cortical auxin fieldTransport Steppin3_emergence_export

Annotons

PIN3: auxin efflux transmembrane transporter activity

pin3_emergence_efflux

Participant: Gene Product: PIN3

Gene Product:

PIN3UniProtKB:Q9S7Z8

Family:

PIN3 classificationPANTHER:PTHR31752:SF60 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: PIN3UniProtKB:Q9S7Z8

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

PIN3 acts in the early auxin-induced transporter phase overlying lateral-root primordia; this emergence context is distinct from endodermal reflux during initiation.

PMID:35917926

PIN3 structure and transport experiments support auxin exporter activity.

Part 2: LAX3 uptake in selected overlying cell files

LAX3 uptake in selected overlying cell filesTransport Steplax3_emergence_import

Annotons

LAX3: auxin influx transmembrane transporter activity

lax3_influx

Participant: Gene Product: LAX3

Gene Product:

LAX3UniProtKB:Q9CA25

Family:

LAX3 classificationPANTHER:PTHR48017 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: LAX3UniProtKB:Q9CA25

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin influx transmembrane transporter activityGO:0010328

Processes

auxin import into cellGO:0060919

Locations

plasma membraneGO:0005886

LAX3 uptake reinforces localized auxin response and downstream cell-wall remodeling in overlying cells. It is not itself a wall-remodeling enzyme.

PMID:40759769

Full-length LAX3 supports auxin uptake; the structural 44–470 construct is inactive, and fixed proton stoichiometry was not measured.

Arabidopsis PIN1–ABCB19 coordinated exportBiological Processarabidopsis_pin1_abcb19_cooperation

A cooperative two-carrier implementation, not an obligatory heterocomplex or a requirement for all PIN-mediated transport.

Context

Arabidopsis thalianaNCBITaxon:3702

Cells and PM domains where PIN1 and ABCB19 expression overlaps

Connections

abcb_auxin_export -> pin1_cooperative_export Positively Regulates

ABCB19 supports PIN1 membrane stability in the assayed overlapping domains. This pair-specific effect is not extended to every PIN or ABCB; independent transport remains possible. The observed support concerns membrane organization; ABCB19 efflux chemistry is not independently established as the cause of PIN1 activation.

PMID:18774968

Native membrane-domain observations support ABCB19 stabilization of PIN1 in sites of overlapping expression.

Part 1: ABCB19 transport and PIN1 membrane stabilization

ABCB19 transport and PIN1 membrane stabilizationTransport Stepabcb_auxin_export

Annotons

ABCB19: auxin efflux transmembrane transporter activity

abcb19_auxin_export

Participant: Gene Product: ABCB19

Gene Product:

ABCB19UniProtKB:Q9LJX0

Family:

ABCB19 classificationPANTHER:PTHR43394:SF11 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: ABCB19UniProtKB:Q9LJX0

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

ABCB19 provides IAA export and supports PIN1 membrane organization where their expression overlaps. ABCB19 also transports brassinosteroids; substrate exclusivity is not asserted.

PMID:17237354

Native localization and heterologous transport experiments support tissue-specific coordinated and independent PIN/ABCB transport.

Part 2: PIN1 export in overlapping membrane domains

PIN1 export in overlapping membrane domainsTransport Steppin1_cooperative_export

Annotons

PIN1: auxin efflux transmembrane transporter activity

pin1_efflux

Participant: Gene Product: PIN1

Gene Product:

PIN1UniProtKB:Q9C6B8

Family:

PIN1 classificationPANTHER:PTHR31752:SF18 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: PIN1UniProtKB:Q9C6B8

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

PIN1 exports auxin; its native membrane-face polarity depends on cell and organ context, including basal vascular and convergent shoot-apex patterns.

PMID:35917925

PIN1 in HEK293F cells supports IAA efflux enhanced by D6PK and inhibited by NPA.

Arabidopsis D6PK-regulated PIN3 exportBiological Processarabidopsis_d6pk_pin3

Two substantive activities: protein phosphorylation and auxin export. Native tissue role and heterologous direct activity evidence are distinguished.

Context

Arabidopsis thalianaNCBITaxon:3702

Hypocotyl basipetal auxin transport and phototropic bending

PMID:23709629

Native D6PK-family mutants show reduced PIN3 phosphorylation and hypocotyl basipetal transport; the specific D6PK/PIN3 activation is supported independently by direct assays.

This is accompanied by a reduction of basipetal auxin transport in the hypocotyls of d6pk as well as in pin mutants.

Connections

d6pk_pin_regulation -> d6pk_pin3_export Positively Regulates

D6PK phosphorylation increases the carrier export activity in the assayed pairing; this edge means activity activation, not a universal apical relocation or kinase requirement for every PIN.

PMID:24948515

D6PK and PID directly activate PIN-mediated auxin transport, with different phosphosite preferences.

Part 1: D6PK kinase activation

D6PK kinase activationRegulatory Stepd6pk_pin_regulation

Annotons

D6PK: protein serine/threonine kinase activity

d6pk_pin_activation

Participant: Gene Product: D6PK

Gene Product:

D6PKUniProtKB:Q9FG74

Family:

D6PK classificationPANTHER:PTHR45637 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: D6PKUniProtKB:Q9FG74

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

protein serine/threonine kinase activityGO:0004674

Processes

regulation of auxin polar transportGO:2000012

Locations

plasma membraneGO:0005886

D6PK is basally PM-associated and directly activates transport without being a universal polarity-switch kinase.

PMID:24948515

Oocyte transport and phosphorylation assays distinguish kinase-active from inactive D6PK/PID and identify PIN phosphosite-dependent activation.

phosphorylation of conserved phosphosites is required for the efficient activation of PIN1 and PIN3.

Part 2: PIN3 efflux regulated by D6PK

PIN3 efflux regulated by D6PKTransport Stepd6pk_pin3_export

Annotons

PIN3: auxin efflux transmembrane transporter activity

d6pk_pin3_efflux

Participant: Gene Product: PIN3

Gene Product:

PIN3UniProtKB:Q9S7Z8

Family:

Representative Members: PIN3UniProtKB:Q9S7Z8

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

The specified kinase/carrier pairing is an assayed activation module; other plant factors and native tissue geometry determine the resulting auxin stream.

PMID:24948515

Direct PIN1/PIN3 transport activation in Xenopus oocytes is supported by kinase coexpression and phosphosite analysis.

Arabidopsis PID-regulated PIN1 exportBiological Processarabidopsis_pid_pin1

Two substantive activities: protein phosphorylation and auxin export. Native tissue role and heterologous direct activity evidence are distinguished.

Context

Arabidopsis thalianaNCBITaxon:3702

PIN1 polarity in native Arabidopsis developmental transport contexts

PMID:15514156

Native PID perturbation changes PIN polarity and auxin-flow patterns; its biochemical activation of PIN1 is distinct from the tissue-specific consequences of that polarity change.

Connections

pid_pin_regulation -> pid_pin1_export Positively Regulates

PID phosphorylation increases the carrier export activity in the assayed pairing; this edge means activity activation, not a universal apical relocation or kinase requirement for every PIN.

PMID:24948515

D6PK and PID directly activate PIN-mediated auxin transport, with different phosphosite preferences.

Part 1: PID kinase activation

PID kinase activationRegulatory Steppid_pin_regulation

Annotons

PID: protein serine/threonine kinase activity

pid_pin_activation

Participant: Gene Product: PID

Gene Product:

PIDUniProtKB:O64682

Family:

PID classificationPANTHER:PTHR45637 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: PIDUniProtKB:O64682

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

protein serine/threonine kinase activityGO:0004674

Processes

regulation of auxin polar transportGO:2000012

Locations

plasma membraneGO:0005886

PID phosphorylates PINs and can influence their targeting; PID/WAG localization need not itself be apical. Polarity effects are not equivalent to a uniformly positive tissue-flux change.

PMID:24948515

Oocyte transport and phosphorylation assays distinguish kinase-active from inactive D6PK/PID and identify PIN phosphosite-dependent activation.

Part 2: PIN1 efflux regulated by PID

PIN1 efflux regulated by PIDTransport Steppid_pin1_export

Annotons

PIN1: auxin efflux transmembrane transporter activity

pid_pin1_efflux

Participant: Gene Product: PIN1

Gene Product:

PIN1UniProtKB:Q9C6B8

Family:

Representative Members: PIN1UniProtKB:Q9C6B8

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

The specified kinase/carrier pairing is an assayed activation module; other plant factors and native tissue geometry determine the resulting auxin stream.

PMID:24948515

Direct PIN1/PIN3 transport activation in Xenopus oocytes is supported by kinase coexpression and phosphosite analysis.

Arabidopsis TWD1-regulated ABCB1 transportBiological Processarabidopsis_twd1_abcb1

A regulator-plus-transporter mechanism. Native stamen localization, abundance and auxin-response patterns support the physiological setting; they are not direct native flux-rate measurements. Conditional CaM-dependent catalysis of an isolated TWD1 fragment in a 2026 preprint does not define this route.

Context

Arabidopsis thalianaNCBITaxon:3702

TWD1/ABCB-regulated transport, including the studied stamen-elongation context

PMID:35512423

Native stamen mutants, rescue, protein localization/abundance and DR5 profiles support TWD1/ABCB1 function during reproductive growth; the directional flow model is inferred rather than a direct native isotope-flux measurement.

Connections

twd1_abcb1_activation -> abcb1_twd1_dependent_export Positively Regulates

TWD1 positively regulates this ABCB in the specified experimental and native context. This is transporter activation, not an assertion that an ABCB proline bond was directly shown to be isomerized in vivo.

PMID:32699109

Direct TWD1-dependent ABCB1 transport activation is distinguished from native abundance/localization effects, which are independently studied in PMID:35512423.

Part 1: TWD1 activation of ABCB1

TWD1 activation of ABCB1Regulatory Steptwd1_abcb1_activation

Annotons

FKBP42: transporter activator activity

twd1_abcb1_regulator

Participant: Gene Product: FKBP42

Gene Product:

FKBP42UniProtKB:Q9LDC0

Family:

FKBP42 classificationPANTHER:PTHR11242:SF0 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: FKBP42UniProtKB:Q9LDC0

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

transporter activator activityGO:0141109

Processes

regulation of auxin polar transportGO:2000012

Locations

plasma membraneGO:0005886

TWD1/FKBP42 positively regulates transporter activity; its trafficking/chaperone effects and possible isomerase mechanism are not collapsed into a settled full-length native PPIase claim.

PMID:32699109

Direct ABCB1 activation by TWD1 is assayed in heterologous cells; native stamen context is independently supported by PMID:35512423.

Part 2: ABCB1 export in the TWD1-regulated context

ABCB1 export in the TWD1-regulated contextTransport Stepabcb1_twd1_dependent_export

Annotons

ABCB1: auxin efflux transmembrane transporter activity

abcb1_twd1_efflux

Participant: Gene Product: ABCB1

Gene Product:

ABCB1UniProtKB:Q9ZR72

Family:

ABCB1 classificationPANTHER:PTHR43394:SF11 Classification of this exact exemplar only. Neither substrate specificity, native polarity nor regulatory pairing is assigned to every member of this family or subfamily.

Representative Members: ABCB1UniProtKB:Q9ZR72

Taxon:

Arabidopsis thalianaNCBITaxon:3702

Function

auxin efflux transmembrane transporter activityGO:0010329

Processes

auxin export across the plasma membraneGO:0010315

Locations

plasma membraneGO:0005886

IAA export in the tested TWD1-regulated context; this does not make TWD1 universally obligatory for all transport assays or exclude other ABCB substrates.

PMID:32699109

ABCB1 IAA-export activation and the tested D/E-P motif support the transporter-regulator pairing; native reproductive context is evaluated separately.