User:Alice Harmon/Sandbox 5: Difference between revisions

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Abscisic acid (ABA,)[[Image:Abscisic acid.svg.png|thumb| Abscisic Acid]] is a plant hormone that regulates seed dormancy and germination, stomatal closure, and responses to drought stress, and its core signaling pathway has recently been identified.<ref>PMID:15012233</ref><ref>PMID:12045268</ref><ref>PMID:20192755</ref> In Arabidopsis, this pathway involves an ABA receptor (PYR1, PYR2, PYL1, PYL2, and RCAR), a protein phosphatase 2C in Clade C (ABI1, ABI2, and HAB1), and a protein kinase in subclass III of SnRK2s ([[SnRK2.6/OST1/SRK2E]], SNRK2.2/SRK2D and SnRK2.3/SRK2IA).<ref name = "Mustilli2002">PMID:12468729</ref><ref>PMID:12514244</ref><ref name = "Nakashima2009">PMID:19541597</ref><ref name = "Fujii2007">PMID:17307925</ref>

As shown in the left ~~figure, when~~ the ABA level in the cytosol is low, the ABA receptor (R) is an unliganded monomer, and the SNRK2 protein kinase (K) is bound to a protein phosphatase 2C (P) in a complex (K-P) in which the kinase is dephosphorylated and inactivated by the phosphatase. ABA binds to the ABA receptor (R)<ref>PMID:19893533</ref><ref>PMID:19407143</ref><ref>PMID:19407142</ref>. The activated receptor (R.ABA) binds to a protein phosphatase 2C (R.ABA-P), and frees the protein kinase to be activated by autophosphorylation or phosphorylation by another protein kinase. Activation of SnRK2.6/OST1/SRK2E leads to phosphorylation of: 1) ion channels SLAC1<ref>PMID: 19955405</ref> and KAT1<ref>PMID:19785574</ref> in guard cells and stomatal closure; 2) transcription factor ABI5<ref name = "Nakashima2009"/> in seeds/seedlings and dormancy/growth arrest; or 3) phosphorylation of transcription factor AREB/ABF <ref>PMID: 16446457</ref><ref name = "Fujii2007"/> in vegetative tissue and stress tolerance and growth regulation.

The core ABA signaling pathway is shown in the figure to the left. When the ABA level in the cytosol is low, the ABA receptor (R) is an unliganded dimer<ref>PMID:19933100</ref><ref>PMID:23265948</ref> (monomer shown), and the SNRK2 protein kinase (K) is bound to a protein phosphatase 2C (P) in a complex (K-P) in which the kinase is dephosphorylated and inactivated by the phosphatase. When the ABA level rises ABA binds to the ABA receptor (R)<ref>PMID:19893533</ref><ref>PMID:19407143</ref><ref>PMID:19407142</ref>. The activated receptor (R.ABA) binds to a protein phosphatase 2C<ref>PMID:19624469</ref> (R.ABA-P), and frees the protein kinase to be activated by autophosphorylation or phosphorylation by another protein kinase. Activation of SnRK2.6/OST1/SRK2E leads to phosphorylation of: 1) ion channels SLAC1<ref>PMID: 19955405</ref> and KAT1<ref>PMID:19785574</ref> in guard cells and stomatal closure; 2) transcription factor ABI5<ref name = "Nakashima2009"/> in seeds/seedlings and dormancy/growth arrest; or 3) phosphorylation of transcription factor AREB/ABF <ref>PMID: 16446457</ref><ref name = "Fujii2007"/> in vegetative tissue and stress tolerance and growth regulation.

Structures in the figure are: R, apo PYR2, [[3kdh]]; R.ABA, PYR2.ABA, [[3kdi]]; K-P; SnRK2.6-HAB1, [[3ujg]]; R.ABA-P, PYR2.ABA-ABI2, [[3ujl]]; K, SnRK2.6,[[3uc4]].

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 Abscisic acid (ABA,)[[Image:Abscisic acid.svg.png|thumb| Abscisic Acid]] is a plant hormone that regulates seed dormancy and germination, stomatal closure, and responses to drought stress, and its core signaling pathway has recently been identified.<ref>PMID:15012233</ref><ref>PMID:12045268</ref><ref>PMID:20192755</ref> In Arabidopsis, this pathway involves an ABA receptor (PYR1, PYR2, PYL1, PYL2, and RCAR), a protein phosphatase 2C in Clade C (ABI1, ABI2, and HAB1), and a protein kinase in subclass III of SnRK2s ([[SnRK2.6/OST1/SRK2E]], SNRK2.2/SRK2D and SnRK2.3/SRK2IA).<ref name = "Mustilli2002">PMID:12468729</ref><ref>PMID:12514244</ref><ref name = "Nakashima2009">PMID:19541597</ref><ref name = "Fujii2007">PMID:17307925</ref>
-As shown in the left figure, when the ABA level in the cytosol is low, the ABA receptor (R) is an unliganded monomer, and the SNRK2 protein kinase (K) is bound to a protein phosphatase 2C (P) in a complex (K-P) in which the kinase is dephosphorylated and inactivated by the phosphatase.  ABA binds to the ABA receptor (R)<ref>PMID:19893533</ref><ref>PMID:19407143</ref><ref>PMID:19407142</ref>. The activated receptor (R<sup>.</sup>ABA) binds to a protein phosphatase 2C (R<sup>.</sup>ABA-P), and frees the protein kinase to be activated by autophosphorylation or phosphorylation by another protein kinase. Activation of SnRK2.6/OST1/SRK2E leads to phosphorylation of: 1) ion channels SLAC1<ref>PMID: 19955405</ref> and KAT1<ref>PMID:19785574</ref> in guard cells and stomatal closure; 2)  transcription factor ABI5<ref name = "Nakashima2009"/> in seeds/seedlings and dormancy/growth arrest; or 3) phosphorylation of transcription factor AREB/ABF <ref>PMID: 16446457</ref><ref name = "Fujii2007"/> in vegetative tissue and stress tolerance and growth regulation.
+The core ABA signaling pathway is shown in the figure to the left. When the ABA level in the cytosol is low, the ABA receptor (R) is an unliganded dimer<ref>PMID:19933100</ref><ref>PMID:23265948</ref> (monomer shown), and the SNRK2 protein kinase (K) is bound to a protein phosphatase 2C (P) in a complex (K-P) in which the kinase is dephosphorylated and inactivated by the phosphatase.  When the ABA level rises ABA binds to the ABA receptor (R)<ref>PMID:19893533</ref><ref>PMID:19407143</ref><ref>PMID:19407142</ref>. The activated receptor (R<sup>.</sup>ABA) binds to a protein phosphatase 2C<ref>PMID:19624469</ref> (R<sup>.</sup>ABA-P), and frees the protein kinase to be activated by autophosphorylation or phosphorylation by another protein kinase. Activation of SnRK2.6/OST1/SRK2E leads to phosphorylation of: 1) ion channels SLAC1<ref>PMID: 19955405</ref> and KAT1<ref>PMID:19785574</ref> in guard cells and stomatal closure; 2)  transcription factor ABI5<ref name = "Nakashima2009"/> in seeds/seedlings and dormancy/growth arrest; or 3) phosphorylation of transcription factor AREB/ABF <ref>PMID: 16446457</ref><ref name = "Fujii2007"/> in vegetative tissue and stress tolerance and growth regulation.
 Structures in the figure are: R, apo PYR2, [[3kdh]];  R<sup>.</sup>ABA, PYR2<sup>.</sup>ABA, [[3kdi]]; K-P; SnRK2.6-HAB1, [[3ujg]]; R<sup>.</sup>ABA-P, PYR2<sup>.</sup>ABA-ABI2, [[3ujl]]; K, SnRK2.6,[[3uc4]].