Gene Ontology annotation through association of InterPro records with GO terms
Annotation inferences using phylogenetic trees
Electronic Gene Ontology annotations created by ARBA machine learning models
Combined Automated Annotation using Multiple IEA Methods
The nitrate transporter AtNRT1.1 (CHL1) functions in stomatal opening and contributes to drought susceptibility in Arabidopsis.
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CHL1 functions in stomatal opening; chl1 mutants show reduced transpiration and enhanced drought tolerance.
"Compared with wild-type plants, chl1 mutants had reduced stomatal opening and reduced transpiration rates in the light or when deprived of CO(2) in the dark."
The Arabidopsis NRT1.1 transporter participates in the signaling pathway triggering root colonization of nitrate-rich patches.
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Native mutants have impaired nitrate-patch root colonization independent of reduced uptake or simple nutritional rescue, supporting a nitrate-response role.
"These results show that NRT1.1 promotes localized root proliferation independently of any nutritional effect and indicate a role in the ANR1-dependent NO(3)(-) signaling pathway, either as a NO(3)(-) sensor or as a facilitator of NO(3)(-) influx into NO(3)(-)-sensing cells."
CHL1 functions as a nitrate sensor in plants.
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CHL1 functions as a nitrate sensor (transceptor); the sensing function is separable from uptake activity and is controlled by CIPK23 phosphorylation of Thr101.
"analysis of an uptake- and sensing-decoupled mutant showed that the nitrate transporter CHL1 functions as a nitrate sensor."
NRT1.1 Regulates Nitrate Allocation and Cadmium Tolerance in Arabidopsis.
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Full source experiments concern nitrate allocation during cadmium stress, not photoperiodic flowering. The original flowering row has a source mismatch, but independent PMID:33643357 supports the biological claim under measured day-length and nitrate conditions; that mismatch alone does not invalidate the function.
Phosphorylation-Mediated Dynamics of Nitrate Transceptor NRT1.1 Regulate Auxin Flux and Nitrate Signaling in Lateral Root Growth.
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Native phosphovariant comparisons combine lateral-root auxin redistribution, imaging and trafficking with heterologous yeast influx measurements. This directly supports conditional auxin transport and membrane regulation; tissue-level basipetal movement is distinct from cellular efflux.
"Net IAA influx profile (C) and average net auxin flux (D) in yeast strains expressing empty vector (CK), NRT1.1, T101A, and T101D measured by NMT assay."
The Arabidopsis CHL1 protein plays a major role in high-affinity nitrate uptake.
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Native chl1 mutants lose high- and low-affinity nitrate uptake, with altered nitrate-dependent membrane depolarization.
"Further analysis showed that chl1 mutants have reduced high-affinity uptake in induced plants and are missing a saturable component of the constitutive, high-affinity uptake system in addition to reduced low-affinity uptake."
The herbicide sensitivity gene CHL1 of Arabidopsis encodes a nitrate-inducible nitrate transporter.
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Direct electrogenic nitrate uptake in oocytes.
"Injection of CHL1 mRNA into Xenopus oocytes produces a nitrate- and pH-dependent membrane depolarization, inward current, and nitrate uptake."
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CHL1 was identified via chlorate (herbicide) sensitivity and encodes a nitrate-inducible nitrate transporter.
"These data show that the CHL1 gene encodes an electrogenic nitrate transporter."
Nitrate-regulated auxin transport by NRT1.1 defines a mechanism for nutrient sensing in plants.
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Nitrate inhibits NPF6.3-facilitated auxin uptake and changes lateral-root auxin accumulation.
"NRT1.1 not only transports nitrate but also facilitates uptake of the phytohormone auxin."
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NRT1.1/CHL1 facilitates auxin transport in a nitrate-regulated manner, linking nitrate availability to root development.
"NRT1.1 not only transports nitrate but also facilitates uptake of the phytohormone auxin."
Molecular basis of nitrate uptake by the plant nitrate transporter NRT1.1.
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Nitrate recognition differs from peptide transporters; Ala-Ala binding is negative.
"does not recognize nitrite, alanine, sulphate, phosphate or the di-peptide Ala-Ala"
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Structural and mutagenesis analysis (Arg45, Thr101, Lys164, His356) defines the molecular basis of nitrate uptake by NRT1.1/CHL1.
"We mutated all three of these positively charged residues to alanine, however mutation of only His356 resulted in complete loss of nitrate binding"
Crystal structure of the plant dual-affinity nitrate transporter NRT1.1.
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Structure and cell-based FRET support phosphorylation-controlled oligomeric regulation.
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The crystal structure of NRT1.1/CHL1 reveals an MFS-fold nitrate transporter; mutagenesis defines the nitrate-binding pocket and proton-coupling machinery.
"His356 on TMH7 is the only polar residue that is in close contact with nitrate"
Improved Plant Nitrate Status Involves in Flowering Induction by Extended Photoperiod.
Nitrate Transporter 1.1 is involved in regulating flowering time via transcriptional regulation of FLOWERING LOCUS C in Arabidopsis thaliana.
UniProtKB Q05085 NPF6.3 reviewed record
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The publication-linked curated record supports bidirectional nitrate transport and root-to-shoot nitrate translocation (including PMID:23645597), without establishing an auxin efflux activity.
"Acts as a bidirectional transporter involved in root-to-shoot nitrate translocation."
CHL1 is a dual-affinity nitrate transporter of Arabidopsis involved in multiple phases of nitrate uptake.
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CHL1-injected oocytes display biphasic nitrate uptake, with approximately 50 micromolar and 4 millimolar affinity phases; native mutant and complementation experiments support dual-affinity uptake.
"Kinetic analysis of nitrate uptake by CHL1-injected Xenopus oocytes displayed a biphasic pattern with a Michaelis-Menten Km value of approximately 50 microM for the high-affinity phase and approximately 4 mM for the low-affinity phase."
Transcript profiling in the chl1-5 mutant of Arabidopsis reveals a role of the nitrate transporter NRT1.1 in the regulation of another nitrate transporter, NRT2.1.
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NRT1.1 mutation alters NRT2.1 repression and high-affinity uptake regulation. This early study discusses both nutritional-feedback and direct-signaling explanations, rather than itself resolving nitrate sensing.
"This indicates that NRT1.1 plays an unexpected but important role in the regulation of both NRT2.1 expression and NO(3)(-) HATS activity."
Arabidopsis NRT1.1 is a bidirectional transporter involved in root-to-shoot nitrate translocation.
Falcon (Edison Scientific) deep research report: Arabidopsis thaliana NPF6.3 (CHL1/NRT1.1; At1g12110; UniProt Q05085) functional annotation
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"NPF6.3/CHL1/NRT1.1 is widely regarded as a **dual-affinity** nitrate transporter with **biphasic kinetics**, enabling transport across a wide external nitrate range."
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"A core concept in nitrate biology is that NPF6.3 acts as a **transceptor**—a transporter with receptor-like signaling capability—helping initiate the **primary nitrate response (PNR)** and modulating expression of other nitrate transport genes (e.g., **NRT2.1**) and developmental programs."
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"NPF6.3 is described as a **proton-coupled nitrate symporter**."
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"A central and well-supported mechanism is that **Thr101** serves as an affinity-mode switch: phosphorylation favors high-affinity transport, whereas dephosphorylation favors low-affinity transport."
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"Nitrate-induced Ca2+ signals are perceived by **CBL1/CBL9**, activating **CIPK23**, which phosphorylates NRT1.1 at Thr101 and shifts apparent affinity from **Km ~4 mM** to **Km ~40 µM**."
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"localizes to the **plasma membrane** of **root epidermal** and **vascular** cells, with additional localization reported in **guard cells**"
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"NRT1.1 facilitates basipetal auxin transport and negatively regulates auxin biosynthesis/transport-related genes (e.g., TAR2, LAX3), thereby removing auxin from lateral root primordia under low nitrate and inhibiting lateral root growth"
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"NRT1.1/NPF6.3 is described as regulating expression of NRT2.1 and other primary nitrate-response genes"
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"Across sources, nitrate (NO3−) is the core substrate, and NPF6.3 contributes substantially to nitrate uptake"
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"The CHL1 name is linked to chlorate resistance screens; chlorate is a nitrate analog used in genetics, supporting the nitrate-related substrate recognition and historical discovery context."
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"AtNPF6.3 has been estimated to contribute roughly 10–80% of whole-plant nitrate uptake."