Sandbox Reserved 935: Difference between revisions
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There is a balance between phosphorylation dependent activation and several potential mechanisms for deactivation of BRI1 <ref name=Oh2012>Man-Ho Oh, Xiaofeng Wang, Steven D. Clouse and Steven C. Huber: Deactivation of the ''Arabidopsis'' Brassinosteroid Insensitive 1(BRI1) receptor kinase by autophosphorylation within the glycine-rich loop. PNAS, January 3, 2012; vol. 109, no. 1, 327–332. Doi: 10.1073/pnas.1108321109</ref>. One of them involves autophosphorylation of serine891 in the ATP binding domain, which is involved in the binding and positioning of ATP. The phosphorylation of this residue reduces, but doesn't completely inhibit, the activity of the kinase domain. When this serine is mutated into aspartate or glutamate (which are residues with negative charge and probably function as phosphomimetics), it results into dwarfed ''Arabidopsis'' plants. Phosphorylation of Serine-891 also reduces autophosphorylation on several other residues that are phosphorylated after brassinosteroid induced activation. The deactivation associated with serine891 phosphorylation seems to play a role in attenuation of signaling rather than maintaining the inactive state of BRI1 in the absence of its hormone ligand. | There is a balance between phosphorylation dependent activation and several potential mechanisms for deactivation of BRI1 <ref name=Oh2012>Man-Ho Oh, Xiaofeng Wang, Steven D. Clouse and Steven C. Huber: Deactivation of the ''Arabidopsis'' Brassinosteroid Insensitive 1(BRI1) receptor kinase by autophosphorylation within the glycine-rich loop. PNAS, January 3, 2012; vol. 109, no. 1, 327–332. Doi: 10.1073/pnas.1108321109</ref>. One of them involves autophosphorylation of serine891 in the ATP binding domain, which is involved in the binding and positioning of ATP. The phosphorylation of this residue reduces, but doesn't completely inhibit, the activity of the kinase domain. When this serine is mutated into aspartate or glutamate (which are residues with negative charge and probably function as phosphomimetics), it results into dwarfed ''Arabidopsis'' plants. Phosphorylation of Serine-891 also reduces autophosphorylation on several other residues that are phosphorylated after brassinosteroid induced activation. The deactivation associated with serine891 phosphorylation seems to play a role in attenuation of signaling rather than maintaining the inactive state of BRI1 in the absence of its hormone ligand. | ||
Threonine-872 in the juxtamembrane domain is another phosphorylation site <ref name=Oh2012 />. Its phosphorylation may inhibit the kinase activity and follows soon after the the brassinosteroid activation of the domain. Tyrosine-831 in the juxtamembrane domain is not essential for the activity of the kinase doamain, but it does have a regulatory role <ref name=Oh2009>Man-Ho Oh, Steven D. Clouse and Steven C. Huber: Tyrosine phosphorylation in brassinosteroid signaling. Plant Signaling & Behavior 4:12, 1182-1185; December 2009. PMID: 20514242</ref>. Its phosphorylation causes inhibition of plant growth and delay of flowering. On the other hand, | Threonine-872 in the juxtamembrane domain is another phosphorylation site <ref name=Oh2012 />. Its phosphorylation may inhibit the kinase activity and follows soon after the the brassinosteroid activation of the domain. Tyrosine-831 in the juxtamembrane domain is not essential for the activity of the kinase doamain, but it does have a regulatory role <ref name=Oh2009>Man-Ho Oh, Steven D. Clouse and Steven C. Huber: Tyrosine phosphorylation in brassinosteroid signaling. Plant Signaling & Behavior 4:12, 1182-1185; December 2009. PMID: 20514242</ref>. Its phosphorylation causes inhibition of plant growth and delay of flowering. On the other hand, Tyrosine-956 in the kinase domain is important for kinase activity and its phosphorylation is believed to have an inhibitory role. | ||
==Homologs== | ==Homologs== | ||
