PYR1 (PYRABACTIN RESISTANCE 1; also RCAR11/ABIP6) is the founding member of the PYR/PYL/RCAR family of intracellular abscisic acid (ABA) receptors in Arabidopsis thaliana. It is a small (191 aa) soluble protein with a START/Bet v1-like helix-grip fold that binds the phytohormone ABA within a large internal cavity. PYR1 acts as a homodimer; ABA binding triggers a gate-latch-lock conformational change that closes loops over the hormone and creates a surface enabling the receptor to dock into and inhibit the catalytic site of clade-A type-2C protein phosphatases (PP2Cs such as ABI1, ABI2, HAB1 and AHG3/PP2CA). Because these PP2Cs are negative regulators of ABA signaling, ABA-dependent PP2C inhibition by PYR1 de-represses downstream SnRK2 protein kinases (e.g. OST1/SnRK2.6), driving ABA responses including stomatal closure, inhibition of seed germination, and drought/abiotic-stress tolerance. PYR1 functions chiefly in the cytosol and nucleus; it is also transiently recruited to the plasma membrane by C2-domain CAR proteins and targeted for ubiquitin-mediated vacuolar degradation via the RING E3 ligase RSL1 and FREE1/FYVE1. Its activity is further tuned by phosphorylation (e.g. at Thr78 by the cytosolic ABA receptor kinases CARK1/CARK2/4/5/7/11), which modulates receptor stability, monomerization and ABA-binding affinity. PYR1 can be activated by both natural (+)-ABA and synthetic (-)-ABA, and by the synthetic agonist pyrabactin.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004864 protein phosphatase inhibitor activity | IEA GO_REF:0000117 | ACCEPT | Summary: ABA-bound PYR1 binds to and inhibits clade-A PP2Cs, a defining molecular function of the receptor. This ARBA electronic annotation correctly reflects the experimentally established activity. Reason: Directly supported by experimental work showing ABA-dependent inhibition of PP2C phosphatase activity by PYR1; the IEA is consistent with the curated IDA annotation (PMID:23844015) for the same term. Supporting Evidence: PMID:19407142 (+)-ABA acts as a potent saturable inhibitor of phosphatase activity in the presence of PYR1 (IC50 = 125 nM) file:ARATH/PYR1/PYR1-deep-research-falcon.md intracellular ABA receptor** that binds ABA and inhibits clade A PP2C phosphatases |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: PYR1 is a cytosolic and nuclear ABA receptor; nuclear localization is experimentally documented and this SubCell-mapping IEA is consistent. Reason: Nuclear localization is supported by experimental evidence (UniProt ECO:0000269|PubMed:25465408) and by the family characterization of PYL5 as a cytosolic and nuclear ABA receptor. PYR1 binds CAR proteins both at the plasma membrane and in the nucleus. Supporting Evidence: PMID:19624469 PYL5 is a cytosolic and nuclear ABA receptor |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: Cytoplasmic localization is the principal site of PYR1 action and is supported experimentally; this multi-method IEA is consistent. Reason: Cytoplasm is an experimentally documented location (UniProt ECO:0000269|PubMed:35388459) and the receptor acts as a soluble cytosolic sensor of ABA. Supporting Evidence: PMID:19624469 PYL5 is a cytosolic and nuclear ABA receptor |
| GO:0005773 vacuole | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Vacuolar localization is transient and reflects RSL1/FREE1-mediated targeting of ubiquitylated PYR1 to the vacuolar degradation pathway, not the site where PYR1 perceives ABA or inhibits PP2Cs. Reason: The location is real but represents a regulatory degradation route rather than the core cytosolic/nuclear signaling compartment. UniProt notes PYR1 is "localized transiently in the vacuole when in complex with RSL1". Supporting Evidence: PMID:27495812 FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediates Its Delivery to the Vacuolar Degradation Pathway |
| GO:0005829 cytosol | IEA GO_REF:0000044 | ACCEPT | Summary: Cytosol is a core location of the soluble ABA receptor; the SubCell IEA is consistent with experimental data. Reason: Cytosolic localization is experimentally supported (UniProt ECO:0000269|PubMed:29928509) and consistent with the IDA annotation for the same term (PMID:29928509). Supporting Evidence: PMID:19624469 PYL5 is a cytosolic and nuclear ABA receptor |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Plasma-membrane association is transient and dependent on partner proteins (CAR C2-domain proteins, and the RSL1 E3 ligase), not a constitutive site of PYR1 function. Reason: Membrane localization is documented but conditional: CAR proteins recruit PYR/PYLs to the plasma membrane in a calcium-dependent manner, and RSL1 interacts with PYR1 at the plasma membrane. The core sensing/inhibitory function occurs in the cytosol and nucleus. Supporting Evidence: PMID:25465408 C2-domain abscisic acid-related proteins mediate the interaction of PYR/PYL/RCAR abscisic acid receptors with the plasma membrane |
| GO:0009738 abscisic acid-activated signaling pathway | IEA GO_REF:0000117 | ACCEPT | Summary: PYR1 sits at the apex of the core ABA signaling pathway, perceiving ABA and inhibiting PP2Cs. This is a core biological process annotation. Reason: Strongly supported experimentally; PYR/PYLs are ABA receptors functioning at the apex of the negative regulatory pathway controlling ABA signaling. Consistent with curated IDA annotations for the same term. Supporting Evidence: PMID:19407142 PYR/PYLs are ABA receptors functioning at the apex of a negative regulatory pathway that controls ABA signaling by inhibiting PP2Cs file:ARATH/PYR1/PYR1-deep-research-falcon.md PYR1 is a central receptor within this module |
| GO:0038023 signaling receptor activity | IEA GO_REF:0000117 | ACCEPT | Summary: PYR1 is a bona fide intracellular hormone receptor that binds ABA directly and transduces the signal by inhibiting PP2Cs. Reason: Receptor activity is experimentally established; ABA binds directly to PYR1 within an internal cavity, making it a direct ABA receptor and signal transduction partner. Consistent with the curated IDA/IMP annotations for the same term. Supporting Evidence: PMID:19933100 ABA binds directly to PYR1 within a large internal water-filled cavity, rather than acting as a molecular glue at an interface with PP2Cs file:ARATH/PYR1/PYR1-deep-research-falcon.md engages PP2Cs such as **ABI1** and **HAB1**, functioning as a ligand-dependent inhibitor of PP2Cs |
| GO:0042803 protein homodimerization activity | IEA GO_REF:0000117 | ACCEPT | Summary: PYR1 forms a homodimer (verified by crystallography, SAXS, MALS and in vivo co-IP); homodimerization is integral to its ABA-sequestration mechanism. Reason: Homodimerization is well established; the crystallographic structure reveals a homodimeric assembly verified in vivo by coimmunoprecipitation. Consistent with curated IDA/IPI annotations for the same term. Supporting Evidence: PMID:19933100 The crystallographic structure reveals an alpha/beta helix-grip fold and homodimeric assembly, verified in vivo by coimmunoprecipitation |
| GO:0005515 protein binding | IPI PMID:19407142 Abscisic acid inhibits type 2C protein phosphatases via the ... | REMOVE | Summary: Captures the ABA-dependent PYR1-PP2C (ABI2/ABI1/HAB1) interactions. The bare "protein binding" term is uninformative; the underlying function is the ABA-dependent inhibition of PP2Cs. Reason: Per curation guidelines, generic GO:0005515 is not informative about function. The specific molecular function (binding and inhibiting clade-A PP2Cs) is already captured by GO:0004864 protein phosphatase inhibitor activity (IDA, PMID:23844015). Supporting Evidence: PMID:19407142 we show that ABA binds to PYR1, which in turn binds to and inhibits PP2Cs |
| GO:0005515 protein binding | IPI PMID:19624469 Modulation of drought resistance by the abscisic acid recept... | REMOVE | Summary: Captures PYR1/HAB1 (clade-A PP2C) interaction. Bare protein binding is uninformative; the function is PP2C inhibition. Reason: Generic protein binding is uninformative. The interaction with the clade-A PP2C HAB1 underpins the receptor's PP2C inhibitor activity, which is captured by GO:0004864. Supporting Evidence: PMID:19624469 PYL5 and other members of its protein family inhibited HAB1, ABI1 and ABI2 phosphatase activity in an ABA-dependent manner |
| GO:0005515 protein binding | IPI PMID:19874541 PYR/PYL/RCAR family members are major in-vivo ABI1 protein p... | REMOVE | Summary: Captures the in vivo PYR1-ABI1 (clade-A PP2C) interaction identified by mass spectrometry. Bare protein binding is uninformative. Reason: Generic protein binding is uninformative. The PYR1-ABI1 interaction reflects the receptor's PP2C-inhibitory function (GO:0004864). Supporting Evidence: PMID:19874541 the most robust in planta ABI1-interacting proteins in all LC-MS/MS experiments were nine of the 14 PYR/PYL/RCAR proteins |
| GO:0005515 protein binding | IPI PMID:19898420 A gate-latch-lock mechanism for hormone signalling by abscis... | REMOVE | Summary: Captures the structural PYR1-PP2C (HAB1/ABI1/ABI2) interactions underlying the gate-latch-lock mechanism. Bare protein binding is uninformative. Reason: Generic protein binding is uninformative. The interaction with clade-A PP2Cs is the basis of the receptor's PP2C inhibitor activity (GO:0004864). Supporting Evidence: PMID:19898420 A gate-latch-lock mechanism for hormone signalling by abscisic acid receptors |
| GO:0005515 protein binding | IPI PMID:19898494 The abscisic acid receptor PYR1 in complex with abscisic aci... | REMOVE | Summary: Captures the PYR1-HAB1 (clade-A PP2C) interaction documented alongside the PYR1 crystal structure. Bare protein binding is uninformative. Reason: Generic protein binding is uninformative; the PYR1-PP2C interaction reflects the receptor's PP2C inhibitor activity (GO:0004864) and is also captured by the identical-protein-binding/homodimer annotations for self-association. Supporting Evidence: PMID:19898494 The abscisic acid receptor PYR1 in complex with abscisic acid |
| GO:0005515 protein binding | IPI PMID:20729862 Identification and mechanism of ABA receptor antagonism. | REMOVE | Summary: Captures PYR1-PP2C interactions studied in the context of ABA receptor antagonism. Bare protein binding is uninformative. Reason: Generic protein binding is uninformative; the PP2C-binding/inhibitory function is captured by GO:0004864. Supporting Evidence: PMID:20729862 Identification and mechanism of ABA receptor antagonism |
| GO:0005515 protein binding | IPI PMID:21847091 A thermodynamic switch modulates abscisic acid receptor sens... | REMOVE | Summary: Captures PYR1-PP2C (HAB1) interaction probed in the thermodynamic-switch study. Bare protein binding is uninformative. Reason: Generic protein binding is uninformative; the PP2C interaction is the basis of GO:0004864 and the part_of GO:0062049 complex annotation. Supporting Evidence: PMID:21847091 A thermodynamic switch modulates abscisic acid receptor sensitivity |
| GO:0005515 protein binding | IPI PMID:25652827 Agrochemical control of plant water use using engineered abs... | REMOVE | Summary: Captures PYR1-HAB1 interaction in the context of engineered ABA receptors. Bare protein binding is uninformative. Reason: Generic protein binding is uninformative; PP2C binding/inhibition is the functional readout, captured by GO:0004864. Supporting Evidence: PMID:25652827 Agrochemical control of plant water use using engineered abscisic acid receptors |
| GO:0005515 protein binding | IPI PMID:32612234 Extensive signal integration by the phytohormone protein net... | REMOVE | Summary: Large-scale phytohormone interactome capturing PYR1 interactions (e.g. PP2C P49597, AIP1, TCP19). Bare protein binding is uninformative. Reason: Generic protein binding from a high-throughput interactome study is uninformative about specific function; PP2C interactions are captured by GO:0004864. Supporting Evidence: PMID:32612234 Extensive signal integration by the phytohormone protein network |
| GO:0042802 identical protein binding | IPI PMID:19898494 The abscisic acid receptor PYR1 in complex with abscisic aci... | ACCEPT | Summary: PYR1 self-association (homodimer) verified by the crystal structure of the PYR1 dimer. This is more informative than bare protein binding and supports the homodimerization function. Reason: Identical protein binding reflects experimentally verified PYR1-PYR1 self-association; the crystal structure shows a dimer of PYR1 subunits. Consistent with the GO:0042803 homodimerization annotation. Supporting Evidence: PMID:19898494 the crystal structure of Arabidopsis thaliana PYR1, which consists of a dimer in which one of the subunits is bound to ABA |
| GO:0042802 identical protein binding | IPI PMID:21847091 A thermodynamic switch modulates abscisic acid receptor sens... | ACCEPT | Summary: PYR1 self-association consistent with the dimer-monomer equilibrium that tunes receptor sensitivity. Informative self-interaction term. Reason: Supports PYR1 homodimerization; the thermodynamic-switch study analyzes the PYR1 monomer-dimer equilibrium governing ABA sensitivity. Supporting Evidence: PMID:21847091 A thermodynamic switch modulates abscisic acid receptor sensitivity |
| GO:0005634 nucleus | EXP PMID:25465408 C2-domain abscisic acid-related proteins mediate the interac... | ACCEPT | Summary: Experimental evidence places PYR1 in the nucleus; PYR1 binds CAR proteins both at the plasma membrane and in the nucleus. A core location. Reason: Experimentally supported nuclear localization (this is the source reference for UniProt's nucleus annotation). The soluble receptor acts in both cytosol and nucleus. Supporting Evidence: PMID:25465408 C2-domain abscisic acid-related proteins mediate the interaction of PYR/PYL/RCAR abscisic acid receptors with the plasma membrane |
| GO:0005773 vacuole | EXP PMID:27495812 FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediate... | KEEP AS NON CORE | Summary: Vacuolar localization reflects FREE1-mediated delivery of ubiquitylated PYR1 to the vacuolar degradation pathway, a regulatory turnover route rather than the sensing compartment. Reason: Real but transient/degradative localization; FREE1/FYVE1 mediates delivery of the ABA receptor to the vacuolar degradation pathway. Supporting Evidence: PMID:27495812 FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediates Its Delivery to the Vacuolar Degradation Pathway |
| GO:0005886 plasma membrane | EXP PMID:25465408 C2-domain abscisic acid-related proteins mediate the interac... | KEEP AS NON CORE | Summary: Experimentally observed plasma-membrane localization is CAR-dependent and transient, not the constitutive site of PYR1 function. Reason: C2-domain CAR proteins mediate calcium-dependent recruitment of PYR/PYL receptors to the plasma membrane; this is a conditional localization layered on the core cytosolic/nuclear pool. Supporting Evidence: PMID:25465408 transient calcium-dependent interactions of PYR/PYL ABA receptors with membranes are |
| GO:0009738 abscisic acid-activated signaling pathway | IDA PMID:19407142 Abscisic acid inhibits type 2C protein phosphatases via the ... | ACCEPT | Summary: Direct experimental evidence that PYR1 functions in the ABA-activated signaling pathway by perceiving ABA and inhibiting PP2Cs. Core BP. Reason: The defining paper establishes PYR1 at the apex of ABA signaling; ABA-bound PYR1 inhibits PP2Cs to activate the pathway. Supporting Evidence: PMID:19407142 PYR/PYLs are ABA receptors functioning at the apex of a negative regulatory pathway that controls ABA signaling by inhibiting PP2Cs |
| GO:0062049 protein phosphatase inhibitor complex | IPI PMID:21847091 A thermodynamic switch modulates abscisic acid receptor sens... | ACCEPT | Summary: PYR1 forms an ABA-dependent inhibitory complex with clade-A PP2Cs (ComplexPortal CPX-1620, PYR1 ABA receptor complex). Accurate cellular-component/complex annotation. Reason: ABA binding promotes formation of stable PYR1-PP2C complexes that inhibit the phosphatase; this is precisely a protein phosphatase inhibitor complex. Supporting Evidence: PMID:21847091 ABA binding to pyrabactin resistance (PYR)/PYR1-like (PYL)/Regulatory Component of Abscisic acid Receptor (RCAR) intracellular receptors promotes the formation of stable complexes with certain protein phosphatases type 2C (PP2Cs) |
| GO:0005515 protein binding | IPI PMID:35388459 Monomerization of abscisic acid receptors through CARKs-medi... | REMOVE | Summary: Captures PYR1 interactions with cytosolic ABA receptor kinases (CARK2/4/5/7/11) that phosphorylate it. Bare protein binding is uninformative; PYR1 is the kinase substrate here. Reason: Generic protein binding is uninformative. The biologically meaningful event is CARK-mediated phosphorylation of PYR1 (PYR1 is the substrate), better described as a PTM/regulation rather than a PYR1 molecular function. Supporting Evidence: PMID:35388459 the members in CARK family function redundantly and differentially in ABA signaling |
| GO:0005737 cytoplasm | IDA PMID:35388459 Monomerization of abscisic acid receptors through CARKs-medi... | ACCEPT | Summary: Experimental cytoplasmic localization of PYR1, consistent with its role as a soluble cytosolic ABA sensor and with CARK association in the cytoplasm. Reason: Cytoplasm is a core location; PYR1 associates with the CARK kinases in the cytoplasm and is the experimental source of UniProt's Cytoplasm location. Supporting Evidence: PMID:35388459 Monomerization of abscisic acid receptors through CARKs-mediated phosphorylation |
| GO:0005515 protein binding | IPI PMID:30967269 CARK6 is involved in abscisic acid to regulate stress respon... | REMOVE | Summary: Captures PYR1 interaction with the cytosolic ABA receptor kinase CARK6. Bare protein binding is uninformative; PYR1 is a kinase substrate/partner here. Reason: Generic protein binding is uninformative; the meaningful relationship is CARK6 acting on the receptor in ABA signaling. Supporting Evidence: PMID:30967269 We confirm that CARK6 interacts with ABA receptors, RCAR11-14 |
| GO:0019207 kinase regulator activity | IDA PMID:19407142 Abscisic acid inhibits type 2C protein phosphatases via the ... | MARK AS OVER ANNOTATED | Summary: This TAIR annotation reflects PYR1's role upstream of SnRK2 kinase activity: by inhibiting PP2Cs, ABA-bound PYR1 indirectly de-represses SnRK2 kinases. The measured molecular activity in the paper is PP2C inhibition, not direct kinase regulation. Reason: PYR1 does not directly bind or regulate a kinase; its effect on SnRK2 kinase activity is indirect, via inhibition of the PP2Cs that repress SnRK2. The direct, experimentally measured molecular function is protein phosphatase inhibitor activity (GO:0004864). Retained but flagged because the term implies a direct kinase-regulatory activity that the data do not show. Supporting Evidence: PMID:19407142 we propose a hypothetical model (Figure 4D) for ABA action in which ABA and PYR/PYLs inhibit PP2Cs, which in turn relieves repression of positive factors such as the SnRK2s |
| GO:0005515 protein binding | IPI PMID:27495812 FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediate... | REMOVE | Summary: Captures the PYR1-FREE1/FYVE1 interaction that routes the receptor to vacuolar degradation. Bare protein binding is uninformative. Reason: Generic protein binding is uninformative; the FREE1 interaction relates to regulated vacuolar degradation of the receptor rather than a core PYR1 molecular function. Supporting Evidence: PMID:27495812 FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediates Its Delivery to the Vacuolar Degradation Pathway |
| GO:0005886 plasma membrane | IDA PMID:25330042 The single-subunit RING-type E3 ubiquitin ligase RSL1 target... | KEEP AS NON CORE | Summary: PYR1 is observed at the plasma membrane in complex with the RSL1 E3 ligase (BiFC). This is a conditional, degradation-associated localization. Reason: The RSL1-PYR1 interaction localizes to the plasma membrane and is linked to ubiquitylation/turnover of the receptor, not its constitutive sensing function. Supporting Evidence: PMID:25330042 bimolecular fluorescent complementation (BiFC) studies showed the RSL1-PYL4 and RSL1-PYR1 interaction is localized to plasma membrane |
| GO:0009705 plant-type vacuole membrane | IDA PMID:27495812 FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediate... | KEEP AS NON CORE | Summary: Vacuolar-membrane localization reflects FREE1-mediated trafficking of ubiquitylated PYR1 toward vacuolar degradation; a regulatory turnover route. Reason: Real but transient/degradative localization tied to FREE1-mediated delivery to the vacuolar degradation pathway, not the cytosolic/nuclear sensing site. Supporting Evidence: PMID:27495812 FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediates Its Delivery to the Vacuolar Degradation Pathway |
| GO:0044389 ubiquitin-like protein ligase binding | IPI PMID:25330042 The single-subunit RING-type E3 ubiquitin ligase RSL1 target... | KEEP AS NON CORE | Summary: PYR1 binds the RING-type E3 ubiquitin ligase RSL1 at the plasma membrane, leading to receptor ubiquitylation and degradation. An informative interaction term (better than bare protein binding) describing a regulatory turnover step. Reason: Experimentally supported interaction with the E3 ligase RSL1; this describes regulated degradation of the receptor rather than its core ABA-sensing/PP2C- inhibitory function. Supporting Evidence: PMID:25330042 a single-subunit RING-type E3 ubiquitin ligase RSL1 that interacts with the PYL4 and PYR1 ABA receptors at the plasma membrane file:ARATH/PYR1/PYR1-deep-research-falcon.md interacts with **PYR1** and promotes its degradation |
| GO:1902584 positive regulation of response to water deprivation | IMP PMID:29970817 The Expression of CARK1 or RCAR11 Driven by Synthetic Promot... | KEEP AS NON CORE | Summary: Overexpression of RCAR11 (=PYR1) increases drought tolerance, supporting a positive role in the response to water deprivation. A downstream physiological role of ABA signaling. Reason: Supported by genetic/overexpression evidence (RCAR11 = PYR1 increases drought tolerance). This is a downstream physiological output of PYR1's core ABA receptor / PP2C-inhibitor activity rather than the molecular core function. Supporting Evidence: PMID:29970817 The Expression of CARK1 or RCAR11 Driven by Synthetic Promoters Increases Drought Tolerance in Arabidopsis thaliana |
| GO:0005515 protein binding | IPI PMID:29928509 CARK1 mediates ABA signaling by phosphorylation of ABA recep... | REMOVE | Summary: Captures the PYR1(RCAR11)-CARK1 interaction; CARK1 phosphorylates PYR1 at Thr78. Bare protein binding is uninformative; PYR1 is the kinase substrate. Reason: Generic protein binding is uninformative. The meaningful event is CARK1- mediated phosphorylation of PYR1, a PTM/regulation of the receptor. Supporting Evidence: PMID:29928509 CARK1 phosphorylates RCAR3/RCAR11 at one conserved threonine site, T77/T78 |
| GO:0005829 cytosol | IDA PMID:29928509 CARK1 mediates ABA signaling by phosphorylation of ABA recep... | ACCEPT | Summary: Experimental cytosolic localization of PYR1, where it interacts with CARK1. Consistent with its role as a soluble cytosolic ABA receptor. Core location. Reason: Cytosol is a core location; this is the experimental source of UniProt's cytosol annotation, and PYR1 interacts with CARK1 in the cytosol. Supporting Evidence: PMID:29928509 CARK1 mediates ABA signaling by phosphorylation of ABA receptors |
| GO:0005515 protein binding | IPI PMID:26719420 Calcium-dependent oligomerization of CAR proteins at cell me... | REMOVE | Summary: Captures the PYR1-CAR4 interaction at the cell membrane. Bare protein binding is uninformative; the CAR interaction underlies conditional membrane recruitment. Reason: Generic protein binding is uninformative; the CAR-protein interaction relates to calcium-dependent membrane recruitment of the receptor (a KEEP_AS_NON_CORE localization), not a core molecular function. Supporting Evidence: PMID:26719420 Calcium-dependent oligomerization of CAR proteins at cell membrane modulates ABA signaling |
| GO:0005634 nucleus | ISM GO_REF:0000122 | ACCEPT | Summary: Sequence-based (AtSubP) prediction of nuclear localization, consistent with the experimentally documented nuclear pool of PYR1. Reason: Predicted nucleus is corroborated by experimental nuclear localization (PMID:25465408); harmless and consistent. Supporting Evidence: PMID:25465408 C2-domain abscisic acid-related proteins mediate the interaction of PYR/PYL/RCAR abscisic acid receptors with the plasma membrane |
| GO:0004864 protein phosphatase inhibitor activity | IDA PMID:23844015 Structural insights into the abscisic acid stereospecificity... | ACCEPT | Summary: Direct biochemical demonstration that ABA-bound PYR/PYLs bind and inhibit group-A PP2Cs (HAB1 etc.). This is the core molecular function of PYR1. Reason: Strong experimental support; ABA-bound dimeric PYLs inhibit group-A PP2Cs, and PYR1 can be activated by both ABA enantiomers to do so. Supporting Evidence: PMID:23844015 dimeric PYLs underwent a pronounced conformational rearrangement, and then bound and inhibited the group A protein phosphatases type 2Cs (PP2C) |
| GO:0005515 protein binding | IPI PMID:25465408 C2-domain abscisic acid-related proteins mediate the interac... | REMOVE | Summary: Captures PYR1 interactions with the C2-domain CAR proteins (CAR1/CAR4). Bare protein binding is uninformative; the CAR interaction underlies membrane recruitment. Reason: Generic protein binding is uninformative; the CAR-protein interaction underlies conditional plasma-membrane recruitment (KEEP_AS_NON_CORE localization), not a core molecular function. Supporting Evidence: PMID:25465408 C2-domain abscisic acid-related proteins mediate the interaction of PYR/PYL/RCAR abscisic acid receptors with the plasma membrane |
| GO:0005515 protein binding | IPI PMID:22829320 Unique drought resistance functions of the highly ABA-induce... | REMOVE | Summary: Captures PYR1 interactions with HAI clade-A PP2Cs in yeast two-hybrid. Bare protein binding is uninformative. Reason: Generic protein binding is uninformative; PP2C binding is captured by the specific PP2C inhibitor activity (GO:0004864). Supporting Evidence: PMID:22829320 The HAI PP2Cs interacted most strongly with PYL5 and PYL7 to -10 of the PYL/RCAR ABA receptor family |
| GO:0009738 abscisic acid-activated signaling pathway | IPI PMID:19407142 Abscisic acid inhibits type 2C protein phosphatases via the ... | ACCEPT | Summary: TAIR annotation (with PP2C AT2G38310/HAB1) placing PYR1 upstream of/within the ABA-activated signaling pathway. Consistent with the core BP role. Reason: PYR1 acts at the apex of ABA signaling by binding and inhibiting PP2Cs; the acts_upstream_of_or_within qualifier is appropriate. Supporting Evidence: PMID:19407142 PYR/PYLs are ABA receptors functioning at the apex of a negative regulatory pathway that controls ABA signaling by inhibiting PP2Cs |
| GO:0005634 nucleus | ISS GO_REF:0000024 | ACCEPT | Summary: Ortholog-based (ISS) nuclear localization, consistent with experimentally documented nuclear localization of PYR1. Reason: Corroborated by experimental nucleus annotation (PMID:25465408); a core location for the receptor. Supporting Evidence: PMID:19624469 PYL5 is a cytosolic and nuclear ABA receptor |
| GO:0005737 cytoplasm | ISS GO_REF:0000024 | ACCEPT | Summary: Ortholog-based (ISS) cytoplasmic localization, consistent with the soluble cytosolic receptor and experimental cytoplasm/cytosol annotations. Reason: Corroborated by experimental cytoplasm/cytosol annotations (PMID:35388459, PMID:29928509); a core location. Supporting Evidence: PMID:19624469 PYL5 is a cytosolic and nuclear ABA receptor |
| GO:0009738 abscisic acid-activated signaling pathway | IDA PMID:19624469 Modulation of drought resistance by the abscisic acid recept... | ACCEPT | Summary: Direct evidence that the receptor activates ABA signaling through inhibition of clade-A PP2Cs. Core BP. Reason: Experimentally supported; the receptor activates ABA signaling via direct inhibition of clade-A PP2Cs. Supporting Evidence: PMID:19624469 PYL5 is a cytosolic and nuclear ABA receptor that activates ABA signaling through direct inhibition of clade A PP2Cs |
| GO:0038023 signaling receptor activity | IDA PMID:19624469 Modulation of drought resistance by the abscisic acid recept... | ACCEPT | Summary: Direct evidence of intracellular ABA receptor activity (saturable ABA binding, ABA-dependent PP2C inhibition). Core MF. Reason: The receptor binds ABA (saturable, ITC-measured for the family) and transduces the signal by inhibiting PP2Cs; bona fide signaling receptor activity. Supporting Evidence: PMID:19624469 Isothermal titration calorimetry revealed saturable binding of (+)ABA to PYL5 |
| GO:0038023 signaling receptor activity | IMP PMID:19933100 Structural mechanism of abscisic acid binding and signaling ... | ACCEPT | Summary: Mutagenesis (K59Q, R116G) that disrupts ABA binding abolishes ABA-triggered receptor function (PP2C binding), supporting receptor activity. Core MF. Reason: Structure-guided mutants designed to disrupt hormone binding lose ABA-triggered interactions with PP2C partners, providing functional (IMP) support for receptor activity. Supporting Evidence: PMID:19933100 Site-directed PYR1 mutants designed to disrupt hormone binding lose ABA-triggered interactions with type 2C protein phosphatase partners in planta |
| GO:0042803 protein homodimerization activity | IPI PMID:19898494 The abscisic acid receptor PYR1 in complex with abscisic aci... | ACCEPT | Summary: Crystal structure shows PYR1 as a homodimer; homodimerization is central to ABA sequestration. Core MF. Reason: Experimentally established homodimer; the PYR1 crystal structure is a dimer. Supporting Evidence: PMID:19898494 the crystal structure of Arabidopsis thaliana PYR1, which consists of a dimer in which one of the subunits is bound to ABA |
| GO:0042803 protein homodimerization activity | IDA PMID:19933100 Structural mechanism of abscisic acid binding and signaling ... | ACCEPT | Summary: Homodimeric assembly verified in vivo by co-immunoprecipitation and by SAXS/MALS in solution. Core MF. Reason: PYR1 forms a homodimer constitutively in vivo (co-IP) and in solution; ABA is not required for dimer formation. Supporting Evidence: PMID:19933100 The crystallographic structure reveals an alpha/beta helix-grip fold and homodimeric assembly, verified in vivo by coimmunoprecipitation |
| GO:0010427 abscisic acid binding | IDA PMID:19407142 Abscisic acid inhibits type 2C protein phosphatases via the ... | ACCEPT | Summary: PYR1 binds ABA directly within its internal cavity (NMR HSQC, later confirmed by crystallography). This is the primary ligand-binding molecular function of the receptor. Core MF. Reason: Direct experimental evidence (HSQC NMR, ABA-induced chemical shifts) that ABA binds PYR1; foundational receptor function and the most specific ligand-binding term available. Supporting Evidence: PMID:19407142 Addition of (+)-ABA alters the HSQC signals for many PYR1 and PYR1P88S residues (Figure 4C, SOM Figures 4 and 5), which shows that ABA binds PYR1 file:ARATH/PYR1/PYR1-deep-research-falcon.md to PYR1 observed by NMR chemical shift perturbations upon ABA addition |
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Q: How do the multiple regulatory routes (CARK phosphorylation, RSL1/FREE1-mediated ubiquitylation and vacuolar degradation, CAR-mediated membrane recruitment) integrate to set PYR1 abundance and ABA sensitivity in vivo?
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