PYR1 (PYRABACTIN RESISTANCE 1; RCAR11) is an intracellular abscisic acid (ABA) receptor in Arabidopsis. Its START/Bet v1-like fold forms a homodimer and binds ABA in an internal cavity. Hormone binding closes the receptor gate and creates a surface that binds and inhibits clade-A type-2C protein phosphatases, including ABI1 and HAB1. This relieves phosphatase suppression of downstream SnRK2 signaling and promotes ABA-responsive transcription and physiological responses. PYR1 acts in the cytosol and nucleus. CAR proteins recruit receptor pools to the plasma membrane, while RSL1 and FREE1 participate in receptor turnover through the vacuolar pathway. CARK1-mediated phosphorylation also regulates PYR1 activity.
| 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: PYR1 nuclear localization is supported by the experimental localization curated from PMID:25465408. PYL5 localization is family context, not evidence for PYR1 localization. Supporting Evidence: PMID:19624469 PYL5 is a cytosolic and nuclear ABA receptor |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | MODIFY | Summary: The cytoplasmic pool is supported, and cytosol is the more precise soluble compartment already established for PYR1 by PMID:29928509. This refines the location without rejecting the original cytoplasmic observation. Reason: The cytoplasmic pool is supported, and cytosol is the more precise soluble compartment already established for PYR1 by PMID:29928509. This refines the location without rejecting the original cytoplasmic observation. Proposed replacements: cytosol Supporting Evidence: PMID:29928509 CARK1 mediates ABA signaling by phosphorylation of ABA receptors |
| 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: The study detects PYR1-ABI1 complexes and PYR1-SnRK2.3 co-immunoprecipitation. These interactions are retained as biological evidence, but bare protein binding adds no specific activity beyond the established receptor and PP2C-inhibitor functions. 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: This study engineers PYR1 to respond to mandipropamid. It informs receptor mechanism and engineering but does not establish mandipropamid sensing by native PYR1. Remove the uninformative generic binding term without denying the measured engineered receptor interaction. 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... | MODIFY | Summary: PYR1 self-association forms a characterized homodimer. Refine identical protein binding to the specific homodimerization activity already experimentally annotated. Reason: PYR1 self-association forms a characterized homodimer. Refine identical protein binding to the specific homodimerization activity already experimentally annotated. Proposed replacements: protein homodimerization activity Supporting Evidence: PMID:19933100 The crystallographic structure reveals an alpha/beta helix-grip fold and homodimeric assembly, verified in vivo by coimmunoprecipitation |
| GO:0042802 identical protein binding | IPI PMID:21847091 A thermodynamic switch modulates abscisic acid receptor sens... | MODIFY | Summary: PYR1 self-association forms a characterized homodimer. Refine identical protein binding to the specific homodimerization activity already experimentally annotated. Reason: PYR1 self-association forms a characterized homodimer. Refine identical protein binding to the specific homodimerization activity already experimentally annotated. Proposed replacements: protein homodimerization activity Supporting Evidence: PMID:19933100 The crystallographic structure reveals an alpha/beta helix-grip fold and homodimeric assembly, verified in vivo by coimmunoprecipitation |
| 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... | MODIFY | Summary: The cytoplasmic pool is supported, and cytosol is the more precise soluble compartment already established for PYR1 by PMID:29928509. This refines the location without rejecting the original cytoplasmic observation. Reason: The cytoplasmic pool is supported, and cytosol is the more precise soluble compartment already established for PYR1 by PMID:29928509. This refines the location without rejecting the original cytoplasmic observation. Proposed replacements: cytosol Supporting Evidence: PMID:29928509 CARK1 mediates ABA signaling by phosphorylation of ABA receptors |
| 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 ... | MODIFY | Summary: The established proximal activity in PMID:19407142 is ABA-dependent PP2C inhibition, which relieves inhibition of SnRK2 kinases. Refine the kinase-regulator interpretation to this directly measured molecular function. PYR1 does associate with SnRK2.3 in co-immunoprecipitation experiments (PMID:19874541); that observation is not evidence that PYR1 directly changes kinase catalysis independently of PP2Cs. Reason: The established proximal activity in PMID:19407142 is ABA-dependent PP2C inhibition, which relieves inhibition of SnRK2 kinases. Refine the kinase-regulator interpretation to this directly measured molecular function. PYR1 does associate with SnRK2.3 in co-immunoprecipitation experiments (PMID:19874541); that observation is not evidence that PYR1 directly changes kinase catalysis independently of PP2Cs. Proposed replacements: protein phosphatase inhibitor activity Supporting Evidence: PMID:19407142 (+)-ABA acts as a potent saturable inhibitor of phosphatase activity in the presence of PYR1 (IC50 = 125 nM) PMID:19874541 PYR1 and SnRK2.3 co-immunoprecipitated equally well in the presence and absence of ABA. |
| 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: The study coexpressed RCAR11/PYR1 and CARK1 using synthetic promoters and observed enhanced drought tolerance. It supports a physiological output of the receptor-kinase combination, not an isolated PYR1 overexpression effect. Retain this precise downstream response term as non-core relative to ABA sensing and PP2C inhibition. 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 binds ABA and directly inhibits PP2Cs, executing the receptor step of ABA signaling. 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 | MODIFY | Summary: The cytoplasmic pool is supported, and cytosol is the more precise soluble compartment already established for PYR1 by PMID:29928509. This refines the location without rejecting the original cytoplasmic observation. Reason: The cytoplasmic pool is supported, and cytosol is the more precise soluble compartment already established for PYR1 by PMID:29928509. This refines the location without rejecting the original cytoplasmic observation. Proposed replacements: cytosol Supporting Evidence: PMID:29928509 CARK1 mediates ABA signaling by phosphorylation of ABA receptors |
| 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 cited paper emphasizes PYL5 and supports the receptor-family mechanism; PYR1 receptor activity itself is independently established by direct ABA binding and structure-guided PYR1 mutants in PMID:19407142 and PMID:19933100. Retain the experimentally curated claim without transferring PYL5-specific ITC measurements to PYR1. 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 PMID:19933100 Site-directed PYR1 mutants designed to disrupt hormone binding lose ABA-triggered interactions with type 2C protein phosphatase partners in planta |
| 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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