AHP1 (ARABIDOPSIS HISTIDINE-CONTAINING PHOSPHOTRANSFER PROTEIN 1; ATHP3) is a small (154 aa) histidine-containing phosphotransfer (HPt) protein of Arabidopsis thaliana that acts as the mobile intermediate of the multistep His-Asp phosphorelay. It receives a phosphoryl group on a conserved histidine from the receiver domains of hybrid sensor histidine kinases - the cytokinin receptors AHK2, AHK3 and CRE1/AHK4, and also CKI1 and ETR1 in interaction assays - and transfers it to the receiver aspartate of response regulators, including the nuclear type-B ARR transcription factors and the type-A ARR feedback regulators. AHP1 complements a yeast ypd1 HPt mutant and is distributed between the cytosol and nucleus. Acting redundantly with AHP2, AHP3 and AHP5, it is a positive regulator of cytokinin signaling; higher-order ahp mutants are cytokinin-insensitive and show defects in growth and, through the CKI1 pathway, in female gametophyte development.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000160 phosphorelay signal transduction system | IBA GO_REF:0000033 | ACCEPT | Summary: AHP1 is a histidine-containing phosphotransfer (HPt) protein that relays phosphoryl groups from hybrid histidine kinases to response regulators in the multistep His-Asp phosphorelay. Reason: Core process of AHP1, supported by phosphorelay complementation in E. coli and yeast and by in vitro phosphotransfer to ARRs. Supporting Evidence: PMID:10050311 Both in vivo and in vitro evidence that each AHP can function as a phospho-transmitting HPt domain with an active histidine site was obtained by employing both the Escherichia coli and yeast His-Asp phosphorelay systems. PMID:10050311 It was also demonstrated that AHPs can interact in vitro with ARRs through the His-Asp phosphotransfer reaction. |
| GO:0000160 phosphorelay signal transduction system | IEA GO_REF:0000002 | ACCEPT | Summary: AHP1 is a histidine-containing phosphotransfer (HPt) protein that relays phosphoryl groups from hybrid histidine kinases to response regulators in the multistep His-Asp phosphorelay. Reason: Core process of AHP1, supported by phosphorelay complementation in E. coli and yeast and by in vitro phosphotransfer to ARRs. Supporting Evidence: PMID:10050311 Both in vivo and in vitro evidence that each AHP can function as a phospho-transmitting HPt domain with an active histidine site was obtained by employing both the Escherichia coli and yeast His-Asp phosphorelay systems. PMID:10050311 It was also demonstrated that AHPs can interact in vitro with ARRs through the His-Asp phosphotransfer reaction. |
| GO:0000160 phosphorelay signal transduction system | IMP PMID:10050311 Histidine-containing phosphotransfer (HPt) signal transducer... | ACCEPT | Summary: AHP1 is a histidine-containing phosphotransfer (HPt) protein that relays phosphoryl groups from hybrid histidine kinases to response regulators in the multistep His-Asp phosphorelay. Reason: Core process of AHP1, supported by phosphorelay complementation in E. coli and yeast and by in vitro phosphotransfer to ARRs. Supporting Evidence: PMID:10050311 Both in vivo and in vitro evidence that each AHP can function as a phospho-transmitting HPt domain with an active histidine site was obtained by employing both the Escherichia coli and yeast His-Asp phosphorelay systems. PMID:10050311 It was also demonstrated that AHPs can interact in vitro with ARRs through the His-Asp phosphotransfer reaction. |
| GO:0005515 protein binding | IPI PMID:10930573 Possible His to Asp phosphorelay signaling in an Arabidopsis... | REMOVE | Summary: GOA IPI row recording an interaction of AHP1 with the response regulator ARR9 (UniProtKB:O80366, from the GOA with/from field). Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. The cached abstract of PMID:10930573 (abstract-only) uses the older ATHP/ATRR nomenclature and does not name ARR9, so no supporting quote is attached; the AHP1-ARR9 result is in full text not available in the cache. |
| GO:0005515 protein binding | IPI PMID:10930573 Possible His to Asp phosphorelay signaling in an Arabidopsis... | REMOVE | Summary: GOA IPI row recording an interaction of AHP1 with the response regulator ARR4 (UniProtKB:O82798, from the GOA with/from field). Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. The cached abstract of PMID:10930573 (abstract-only) uses the older ATHP/ATRR nomenclature and does not name ARR4, so no supporting quote is attached; the AHP1-ARR4 result is in full text not available in the cache. |
| GO:0005515 protein binding | IPI PMID:10930573 Possible His to Asp phosphorelay signaling in an Arabidopsis... | MODIFY | Summary: Interaction of AHP1 with the histidine kinase ETR1. Reason: Generic protein binding is uninformative; the partner is a hybrid histidine kinase, which is captured by protein histidine kinase binding. Proposed replacements: protein histidine kinase binding Supporting Evidence: PMID:10930573 We detected interactions between ETR1 and all ATHPs, and between CKI1 and ATHP1 or ATHP2. |
| GO:0005515 protein binding | IPI PMID:11370868 The response regulator ARR2: a pollen-specific transcription... | REMOVE | Summary: Interaction of AHP1 with the response regulator ARR2. Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. Supporting Evidence: PMID:11370868 Yeast two-hybrid analysis and in vitro interaction studies suggest that ARR2 very probably forms part of a multistep two-component signalling mechanism that includes HPt proteins like AHP1 or AHP2. |
| GO:0005515 protein binding | IPI PMID:15714319 In vitro recombination cloning of entire cDNA libraries in A... | REMOVE | Summary: Interaction of AHP1 with the response regulator ARR1. Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. Supporting Evidence: PMID:15714319 The functionality of the in vitro recombination system for the shuttling of entire libraries was then further tested by protein-protein interaction screens. |
| GO:0005515 protein binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | REMOVE | Summary: Interaction of AHP1 with the response regulator ARR9. Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0005515 protein binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | REMOVE | Summary: Interaction of AHP1 with the response regulator ARR14. Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0005515 protein binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | REMOVE | Summary: Interaction of AHP1 with the response regulator ARR1. Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0005515 protein binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | MODIFY | Summary: Interaction of AHP1 with the histidine kinase AHK3. Reason: Generic protein binding is uninformative; the partner is a hybrid histidine kinase, which is captured by protein histidine kinase binding. Proposed replacements: protein histidine kinase binding Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0005515 protein binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | MODIFY | Summary: Interaction of AHP1 with the histidine kinase AHK2. Reason: Generic protein binding is uninformative; the partner is a hybrid histidine kinase, which is captured by protein histidine kinase binding. Proposed replacements: protein histidine kinase binding Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0005515 protein binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | REMOVE | Summary: Interaction of AHP1 with the response regulator ARR5. Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0005515 protein binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | REMOVE | Summary: Interaction of AHP1 with the response regulator ARR2. Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0005515 protein binding | IPI PMID:18384742 Ethylene signaling: identification of a putative ETR1-AHP1 p... | MODIFY | Summary: Interaction of AHP1 with the histidine kinase ETR1. Reason: Generic protein binding is uninformative; the partner is a hybrid histidine kinase, which is captured by protein histidine kinase binding. Proposed replacements: protein histidine kinase binding Supporting Evidence: PMID:18384742 Fluorescence polarization studies presented here demonstrate a specific interaction of ETR1 with the histidine-containing transfer protein AHP1 |
| GO:0005515 protein binding | IPI PMID:18642946 Toward an interaction map of the two-component signaling pat... | REMOVE | Summary: Interaction of AHP1 with the response regulator ARR1. Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. Supporting Evidence: PMID:18642946 we conducted medium-scale yeast two-hybrid screens focusing on those members of the TCS, which are thought to be involved in cytokinin signaling |
| GO:0005515 protein binding | IPI PMID:18642946 Toward an interaction map of the two-component signaling pat... | REMOVE | Summary: Interaction of AHP1 with the response regulator ARR2. Reason: Generic protein binding is uninformative. AHP1-ARR interactions are the physical basis of phosphotransfer to response regulators, which is already captured by histidine phosphotransfer kinase activity (GO:0009927); GO has no specific term for response-regulator binding. Removal does not imply the interaction is false. Supporting Evidence: PMID:18642946 we conducted medium-scale yeast two-hybrid screens focusing on those members of the TCS, which are thought to be involved in cytokinin signaling |
| GO:0005634 nucleus | IBA GO_REF:0000033 | ACCEPT | Summary: AHP1 is distributed between the cytosol and the nucleus, where it delivers phosphoryl groups to nuclear type-B ARRs. Reason: Nucleocytosolic localization of AHPs is consistently observed; later quantitative work found the distribution to be constitutive rather than cytokinin-induced. Supporting Evidence: PMID:20484973 revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway |
| GO:0005634 nucleus | IDA PMID:17122069 The Arabidopsis histidine phosphotransfer proteins are redun... | ACCEPT | Summary: AHP1 is distributed between the cytosol and the nucleus, where it delivers phosphoryl groups to nuclear type-B ARRs. Reason: Nucleocytosolic localization of AHPs is consistently observed; later quantitative work found the distribution to be constitutive rather than cytokinin-induced. The quoted PMID:17122069 sentence is a background citation of earlier work (Hwang and Sheen 2001, PMID:11574878); it is used here only for AHP1 nuclear presence, and its cytokinin-dependence is recorded as DISPUTED in the finding_review on PMID:11574878. Supporting Evidence: PMID:17122069 AHP1, AHP2, and AHP4 accumulate in the nucleus in response to cytokinin treatment PMID:20484973 revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway |
| GO:0005634 nucleus | IDA PMID:18642946 Toward an interaction map of the two-component signaling pat... | ACCEPT | Summary: AHP1 is distributed between the cytosol and the nucleus, where it delivers phosphoryl groups to nuclear type-B ARRs. Reason: Nucleocytosolic localization of AHPs is consistently observed; later quantitative work found the distribution to be constitutive rather than cytokinin-induced. Supporting Evidence: PMID:20484973 revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: AHP1 is distributed between the cytosol and the nucleus, where it delivers phosphoryl groups to nuclear type-B ARRs. Reason: Nucleocytosolic localization of AHPs is consistently observed; later quantitative work found the distribution to be constitutive rather than cytokinin-induced. Supporting Evidence: PMID:20484973 revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: AHP1 has a substantial cytosolic pool, where it receives phosphoryl groups from membrane-bound receptor kinases. Reason: Cytosolic/cytoplasmic localization of AHPs is consistently observed (persistently nucleo-cytosolic). Supporting Evidence: PMID:20484973 revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway |
| GO:0005737 cytoplasm | IDA PMID:17122069 The Arabidopsis histidine phosphotransfer proteins are redun... | ACCEPT | Summary: AHP1 has a substantial cytosolic pool, where it receives phosphoryl groups from membrane-bound receptor kinases. Reason: Cytosolic/cytoplasmic localization of AHPs is consistently observed (persistently nucleo-cytosolic). Supporting Evidence: PMID:20484973 revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway |
| GO:0005737 cytoplasm | IDA PMID:18642946 Toward an interaction map of the two-component signaling pat... | ACCEPT | Summary: AHP1 has a substantial cytosolic pool, where it receives phosphoryl groups from membrane-bound receptor kinases. Reason: Cytosolic/cytoplasmic localization of AHPs is consistently observed (persistently nucleo-cytosolic). Supporting Evidence: PMID:20484973 revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway |
| GO:0005737 cytoplasm | NAS PMID:11158442 Two types of putative nuclear factors that physically intera... | ACCEPT | Summary: AHP1 has a substantial cytosolic pool, where it receives phosphoryl groups from membrane-bound receptor kinases. Reason: Cytosolic/cytoplasmic localization of AHPs is consistently observed (persistently nucleo-cytosolic). The earlier claim of cytokinin-dependent nucleocytoplasmic shuttling (PMID:11574878) is disputed by later quantitative imaging (see the finding_review on that reference) and is not used as support here. Supporting Evidence: PMID:20484973 revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway |
| GO:0005829 cytosol | IEA GO_REF:0000044 | ACCEPT | Summary: AHP1 has a substantial cytosolic pool, where it receives phosphoryl groups from membrane-bound receptor kinases. Reason: Cytosolic/cytoplasmic localization of AHPs is consistently observed (persistently nucleo-cytosolic). Supporting Evidence: PMID:20484973 revealed that the subcellular localization of the AHPs is persistently nucleo-cytosolic and non-responsive to the state of the cytokinin response pathway |
| GO:0009553 embryo sac development | IGI PMID:20363773 Arabidopsis histidine kinase CKI1 acts upstream of histidine... | KEEP AS NON CORE | Summary: ahp quintuple mutants show severe megagametogenesis defects; AHPs act downstream of the cytokinin-independent histidine kinase CKI1 in female gametophyte development. Reason: Genetic evidence (higher-order mutant) supports involvement, but this is a developmental output of CKI1-AHP-ARR signaling rather than AHP1's specific core function, and AHP1 acts redundantly with other AHPs. Supporting Evidence: PMID:20363773 These results define a genetic pathway consisting of CKI1, AHPs, and type-B ARRs in the regulation of female gametophyte development and vegetative growth. PMID:20363773 Consistently, an ahp1,2-2,3,4,5 quintuple mutant, which contains an ahp2-2 null mutant allele, exhibits severe defects in megagametogenesis |
| GO:0009736 cytokinin-activated signaling pathway | IBA GO_REF:0000033 | ACCEPT | Summary: AHP1 is one of the partially redundant AHPs that act as positive regulators of cytokinin signaling, linking AHK receptors to type-B ARRs. Reason: Core process; higher-order ahp mutants are cytokinin-insensitive. Supporting Evidence: PMID:17122069 These observations provide evidence that AHP1, AHP2, AHP3, and AHP5 each act as a positive regulator of cytokinin signaling and that they act partially redundantly. PMID:12068096 A multistep two-component phosphorelay system with distinct AHK, AHP, and ARR proteins plays a central role in cytokinin signal transduction |
| GO:0009736 cytokinin-activated signaling pathway | IEA GO_REF:0000117 | ACCEPT | Summary: AHP1 is one of the partially redundant AHPs that act as positive regulators of cytokinin signaling, linking AHK receptors to type-B ARRs. Reason: Core process; higher-order ahp mutants are cytokinin-insensitive. Supporting Evidence: PMID:17122069 These observations provide evidence that AHP1, AHP2, AHP3, and AHP5 each act as a positive regulator of cytokinin signaling and that they act partially redundantly. PMID:12068096 A multistep two-component phosphorelay system with distinct AHK, AHP, and ARR proteins plays a central role in cytokinin signal transduction |
| GO:0009736 cytokinin-activated signaling pathway | IMP PMID:17122069 The Arabidopsis histidine phosphotransfer proteins are redun... | ACCEPT | Summary: AHP1 is one of the partially redundant AHPs that act as positive regulators of cytokinin signaling, linking AHK receptors to type-B ARRs. Reason: Core process; higher-order ahp mutants are cytokinin-insensitive. Supporting Evidence: PMID:17122069 These observations provide evidence that AHP1, AHP2, AHP3, and AHP5 each act as a positive regulator of cytokinin signaling and that they act partially redundantly. |
| GO:0009736 cytokinin-activated signaling pathway | TAS PMID:12068096 Two-component signal transduction pathways in Arabidopsis. | ACCEPT | Summary: AHP1 is one of the partially redundant AHPs that act as positive regulators of cytokinin signaling, linking AHK receptors to type-B ARRs. Reason: Core process; higher-order ahp mutants are cytokinin-insensitive. Supporting Evidence: PMID:12068096 A multistep two-component phosphorelay system with distinct AHK, AHP, and ARR proteins plays a central role in cytokinin signal transduction |
| GO:0009825 multidimensional cell growth | IGI PMID:20363773 Arabidopsis histidine kinase CKI1 acts upstream of histidine... | KEEP AS NON CORE | Summary: Higher-order ahp mutants show reduced vegetative growth in the CKI1-AHP pathway. Reason: Pleiotropic growth phenotype of redundant AHP loss; downstream output of phosphorelay signaling. Supporting Evidence: PMID:20363773 These results define a genetic pathway consisting of CKI1, AHPs, and type-B ARRs in the regulation of female gametophyte development and vegetative growth. |
| GO:0009927 histidine phosphotransfer kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: AHP1 accepts a phosphoryl group on its conserved HPt histidine from sensor histidine kinases and transfers it to the receiver aspartate of response regulators; it complements a yeast ypd1 mutant. Reason: Histidine phosphotransfer kinase activity is the defining molecular function of AHP1. Supporting Evidence: PMID:10050311 Both in vivo and in vitro evidence that each AHP can function as a phospho-transmitting HPt domain with an active histidine site was obtained by employing both the Escherichia coli and yeast His-Asp phosphorelay systems. PMID:9804162 Growth retardation of YPD1-disrupted yeast cells was reversed with ATHPs, which indicates that ATHPs function as phosphorelay mediators in yeast cells. |
| GO:0009927 histidine phosphotransfer kinase activity | IDA PMID:10050311 Histidine-containing phosphotransfer (HPt) signal transducer... | ACCEPT | Summary: AHP1 accepts a phosphoryl group on its conserved HPt histidine from sensor histidine kinases and transfers it to the receiver aspartate of response regulators; it complements a yeast ypd1 mutant. Reason: Histidine phosphotransfer kinase activity is the defining molecular function of AHP1. Supporting Evidence: PMID:10050311 Both in vivo and in vitro evidence that each AHP can function as a phospho-transmitting HPt domain with an active histidine site was obtained by employing both the Escherichia coli and yeast His-Asp phosphorelay systems. PMID:10050311 It was demonstrated that AHP1 exhibits in vivo ability to complement a mutational lesion of the yeast YPD1 gene |
| GO:0009927 histidine phosphotransfer kinase activity | IDA PMID:9804162 Characterization of genes for two-component phosphorelay med... | ACCEPT | Summary: AHP1 accepts a phosphoryl group on its conserved HPt histidine from sensor histidine kinases and transfers it to the receiver aspartate of response regulators; it complements a yeast ypd1 mutant. Reason: Histidine phosphotransfer kinase activity is the defining molecular function of AHP1. Supporting Evidence: PMID:9804162 Growth retardation of YPD1-disrupted yeast cells was reversed with ATHPs, which indicates that ATHPs function as phosphorelay mediators in yeast cells. |
| GO:0009927 histidine phosphotransfer kinase activity | IEA GO_REF:0000002 | ACCEPT | Summary: AHP1 accepts a phosphoryl group on its conserved HPt histidine from sensor histidine kinases and transfers it to the receiver aspartate of response regulators; it complements a yeast ypd1 mutant. Reason: Histidine phosphotransfer kinase activity is the defining molecular function of AHP1. Supporting Evidence: PMID:10050311 Both in vivo and in vitro evidence that each AHP can function as a phospho-transmitting HPt domain with an active histidine site was obtained by employing both the Escherichia coli and yeast His-Asp phosphorelay systems. PMID:9804162 Growth retardation of YPD1-disrupted yeast cells was reversed with ATHPs, which indicates that ATHPs function as phosphorelay mediators in yeast cells. |
| GO:0043424 protein histidine kinase binding | IBA GO_REF:0000033 | ACCEPT | Summary: AHP1 physically interacts with the receiver domains of hybrid histidine kinases (cytokinin receptors AHK2/3/4 and the ethylene receptor ETR1), the docking interaction underlying phosphotransfer. Reason: Binding to histidine kinases is the physical basis of the phosphorelay function and is supported by Y2H, coaffinity and fluorescence polarization data. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. PMID:11230563 a phosphorelay interaction between the Arabidopsis His-kinase and histidine-containing phosphotransmitters (AHPs) was also demonstrated for the first time |
| GO:0043424 protein histidine kinase binding | IEA GO_REF:0000002 | ACCEPT | Summary: AHP1 physically interacts with the receiver domains of hybrid histidine kinases (cytokinin receptors AHK2/3/4 and the ethylene receptor ETR1), the docking interaction underlying phosphotransfer. Reason: Binding to histidine kinases is the physical basis of the phosphorelay function and is supported by Y2H, coaffinity and fluorescence polarization data. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. PMID:11230563 a phosphorelay interaction between the Arabidopsis His-kinase and histidine-containing phosphotransmitters (AHPs) was also demonstrated for the first time |
| GO:0043424 protein histidine kinase binding | IPI PMID:10930573 Possible His to Asp phosphorelay signaling in an Arabidopsis... | ACCEPT | Summary: AHP1 physically interacts with the receiver domains of hybrid histidine kinases (cytokinin receptors AHK2/3/4 and the ethylene receptor ETR1), the docking interaction underlying phosphotransfer. Reason: Binding to histidine kinases is the physical basis of the phosphorelay function and is supported by Y2H, coaffinity and fluorescence polarization data. Supporting Evidence: PMID:10930573 We detected interactions between ETR1 and all ATHPs, and between CKI1 and ATHP1 or ATHP2. |
| GO:0043424 protein histidine kinase binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | ACCEPT | Summary: AHP1 physically interacts with the receiver domains of hybrid histidine kinases (cytokinin receptors AHK2/3/4 and the ethylene receptor ETR1), the docking interaction underlying phosphotransfer. Reason: Binding to histidine kinases is the physical basis of the phosphorelay function and is supported by Y2H, coaffinity and fluorescence polarization data. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0043424 protein histidine kinase binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | ACCEPT | Summary: AHP1 physically interacts with the receiver domains of hybrid histidine kinases (cytokinin receptors AHK2/3/4 and the ethylene receptor ETR1), the docking interaction underlying phosphotransfer. Reason: Binding to histidine kinases is the physical basis of the phosphorelay function and is supported by Y2H, coaffinity and fluorescence polarization data. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0043424 protein histidine kinase binding | IPI PMID:16965536 Analysis of protein interactions within the cytokinin-signal... | ACCEPT | Summary: AHP1 physically interacts with the receiver domains of hybrid histidine kinases (cytokinin receptors AHK2/3/4 and the ethylene receptor ETR1), the docking interaction underlying phosphotransfer. Reason: Binding to histidine kinases is the physical basis of the phosphorelay function and is supported by Y2H, coaffinity and fluorescence polarization data. Supporting Evidence: PMID:16965536 An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. |
| GO:0160109 plant gross anatomical part developmental process | IEA GO_REF:0000117 | MARK AS OVER ANNOTATED | Summary: Very general ARBA-derived developmental process annotation. Reason: Too general to be informative; AHP1 affects development indirectly via cytokinin and CKI1 phosphorelay signaling. Supporting Evidence: PMID:17122069 These observations provide evidence that AHP1, AHP2, AHP3, and AHP5 each act as a positive regulator of cytokinin signaling and that they act partially redundantly. |
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Download this section (compressed HTML)Q: Given that AHP localization is constitutively nucleocytosolic, how is the phosphorylated AHP pool partitioned between cytosolic receptors and nuclear type-B ARRs, and does phosphorylation alter AHP nuclear residence time?
Q: Does AHP1 show any receptor preference (AHK2/3/4 versus CKI1 or ETR1) in planta that could explain pathway-specific outputs?
Experiment: Quantify phospho-histidine AHP1 in nuclear and cytosolic fractions after cytokinin treatment using phospho-His-specific antibodies or Phos-tag gels, in wild type and receptor mutants.
Hypothesis: Phospho-His occupancy of AHP1 is the rate-limiting signal reaching nuclear type-B ARRs.
Type: biochemical fractionation
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