Activating Compound | Comment | Organism | Structure |
---|---|---|---|
additional information | CPK21 from Arabidopsis thaliana is biochemically activated in vivo in response to hyper-osmotic stress. No increase in enzyme activity following hypo-osmotic stress or mechanical stress | Arabidopsis thaliana |
Cloned (Comment) | Organism |
---|---|
gene AtCPK21, exon-intron gene structure, transient expression of Strep-tagged wild-type and mutant enzymes in Nicotiana benthamiana leaves | Arabidopsis thaliana |
Protein Variants | Comment | Organism |
---|---|---|
D204A | CPK21 kinase-inactive variant with an amino acid substitution in its active site | Arabidopsis thaliana |
additional information | generation of transgenic Arabidopsis complementation lines coding for tagged CPK21 and CPK21D204A expressed under the control of P35S promotor in the cpk21-1 mutant background. All EF-hand mutants possess reduced activity. Under high calcium conditions, maximum protein kinase activity in all single EF-hand mutant enzymes is about 50% of wild-type CPK21 activity. Mutations of the N-terminal EF-hand pair (EF1/EF2) render the enzyme completely inactive, whereas only residual activity is observed when the C-terminal EF-hand pair (EF3/EF4) is compromised. At the lowest Ca2+ condition, wild-type and the C-terminal EF-hand single mutations still accomplish about 75-80% of the activity compared to respective high Ca2+ conditions. In contrast, only about 30% of residual activity compared to high Ca2+ is observed in CPK21 mutant variants compromised in an N-terminal EF-hand calcium-binding motif. A 3-week salt treatment with 200 mM NaCl causes stunted growth in control plants or CPK23 overexpressing lines but has significantly fewer growth defects in the cpk23 mutant, phenotypes, overview | Arabidopsis thaliana |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Ca2+ | dependent on. The CaM-like domain of CPK21 contains, like calmodulin, four single consensus EF-hand motifs forming two pairs of calciumbinding sites | Arabidopsis thaliana | |
Mg2+ | required | Arabidopsis thaliana |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Arabidopsis thaliana | Q9ZSA2 | - |
- |
Arabidopsis thaliana Col-0 | Q9ZSA2 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant Strep-tagged wild-type and mutant enzymes from Nicotiana benthamiana leaves by affinity chromatography | Arabidopsis thaliana |
Source Tissue | Comment | Organism | Textmining |
---|---|---|---|
leaf | - |
Arabidopsis thaliana | - |
additional information | plant growth conditions and phenotypic analysis of wild-type and mutant plants, overview | Arabidopsis thaliana | - |
seedling | - |
Arabidopsis thaliana | - |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
ATP + histone | - |
Arabidopsis thaliana | ADP + phosphorylated histone | - |
? | |
ATP + histone | - |
Arabidopsis thaliana Col-0 | ADP + phosphorylated histone | - |
? | |
ATP + syntide2 | - |
Arabidopsis thaliana | ADP + phosphorylated syntide2 | - |
? | |
ATP + syntide2 | - |
Arabidopsis thaliana Col-0 | ADP + phosphorylated syntide2 | - |
? |
Synonyms | Comment | Organism |
---|---|---|
calcium-dependent protein kinase | - |
Arabidopsis thaliana |
CPK21 | - |
Arabidopsis thaliana |
serine/threonine protein kinase | - |
Arabidopsis thaliana |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
37 | - |
assay at | Arabidopsis thaliana |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7.4 | - |
assay at | Arabidopsis thaliana |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
ATP | - |
Arabidopsis thaliana |
Organism | Comment | Expression |
---|---|---|
Arabidopsis thaliana | no significant alterations in CPK21 gene expression by drought and salt stress | additional information |
General Information | Comment | Organism |
---|---|---|
evolution | the enzyme belongs to the calcium-dependent protein kinases, that comprise a family of plant serine/threonine protein kinases in which the calcium sensing domain and the kinase effector domain are combined within one molecule | Arabidopsis thaliana |
malfunction | loss-of-function seedlings of cpk21 are more tolerant to hyperosmotic stress and mutant plants show increased stress responses with respect to marker gene expression and metabolite accumulation, phenotypes, overview | Arabidopsis thaliana |
metabolism | role of CPK21 within a calcium-regulated protein kinase network consisting of mutual interfering signaling components | Arabidopsis thaliana |
physiological function | calcium-dependent protein kinases and CBL/CBL interacting protein kinase pairs are able to translate the transient change in the cytosolic free calcium concentration into a phosphorylation signal, CDPKs function in calcium-mediated abiotic stress signaling. CDPKs participate at multiple steps in abscisic acid-dependent and -independent abiotic stress signaling | Arabidopsis thaliana |