Table 2.
Examples of associations between kinase activity and aquaporin regulation.
| Species, AQP | Category (name) |
Evidence | Observations | References |
|---|---|---|---|---|
|
Arabidopsis thaliana, NIP1;1 |
CPK (CPK31) | Subcellular localisation & BiFC assay | Regulates arsenic tolerance | (Ji et al., 2017) |
|
Arabidopsis thaliana, PIP2;1 |
RLK (Feronia) | Xenopus oocyte swelling assay | Reduces H2O transport; regulates cell growth | (Bellati et al., 2016) |
|
Arabidopsis thaliana, PIP2;1 |
STK (OST1/ SnRK2.6) |
In vitro phosphorylation assay | Increased H2O transport; ABA-induced stomatal closure | (Grondin et al., 2015) |
|
Arabidopsis thaliana, PIP2;1 |
RLK (BAK1) | In vitro phosphorylation assay | Increased H2O and H2O2 transport; flg22-induced stomatal closure | (Rodrigues et al., 2017) |
|
Arabidopsis thaliana, PIP2;4 |
RLK (SIRK1) | Protoplast swelling assay | Sucrose-responsive H2O transport | (Wu et al., 2013) |
|
Arabidopsis thaliana, PIP3 |
RLK (BSK8) | Quantitative phosphoproteomics | Uncertain | (Wu et al., 2014) |
|
Arabidopsis thaliana, PIP1;1 & PIP1;2 |
CPK (CPK7) | qPCR in WT and cpk7 Arabidopsis plants | Reduces cellular abundance of AQP protein | (Li et al., 2015) |
|
Arabidopsis thaliana, TIP3;1 |
STK (PKA) | In vitro phosphorylation assay | Increases H2O transport | (Maurel et al., 1995) |
|
Camelina sativa, PIP2;1 & PIP2;6 |
STK | K252a treatment in Xenopus oocytes | Reduces H2O transport | (Jang et al., 2014) |
|
Gentiana scabra, PIP2;2 & PIP2;7 |
CPK (CPK16) | In vitro kinase and cell phosphorylation assays | Reversible flower opening | (Nemoto et al., 2022) |
|
Glycine max, NOD26 |
CPK | Immunochemical isolation | Increases H2O transport; salinity-responsive changes in phosphorylation | (Weaver et al., 1991) |
|
Lens culinaris, α-TIP |
CPK | In vitro phosphorylation assay | Speculative involvement in seed germination | (Harvengt et al., 2000) |
|
Oryza sativa, PIP1;1, PIP1;3 & PIP2;3 |
RLK (LP2) | Firefly luciferase complementation imaging assay | Regulation of drought tolerance | (Wu et al., 2015) |
|
Poplar trichocarpa, AQUA1 |
PI3K | Wortmannin treatment in Arabidopsis protoplasts a | Increases the number of AQUA1 cytosolic vesicles under Zn stress; changes membrane localisation | (Ariani et al., 2019) |
| Solanum lycopersicum, PIPs | PI3K | Wortmannin treatment in Arabidopsis protoplasts a | Reduces root hydraulic conductivity under salt stress through decreased water transport | (Jia et al., 2020) |
|
Spinacia oleracea, PM28a |
STK | K252a treatment in Xenopus oocytes | Increases H2O transport | (Johansson et al., 1998) |
|
Spinacia oleracea, PIP2;1 |
CPK | In vitro phosphorylation assay | Increases H2O transport | (Sjövall-Larsen et al., 2006) |
Wortmannin is a specific inhibitor of PI3Ks but may also be involved in inhibiting other kinases.
Protein kinases are key regulatory enzymes involved in attaching a phosphate group to a protein. CPK (Ca2+ dependent protein kinase); RLK (receptor-like kinase); STK (serine/threonine protein kinase); PI3K (phosphatidylinositol 3-kinase). Previous studies have reported kinases and phosphorylation sites relevant to the regulation of mammalian aquaporins (see Nesverova and Törnroth-Horsefield, 2019). There are types of kinases, like protein kinase A (PKA), that are relevant to regulation of both mammalian and plant aquaporins. PKAs activity is dependent on cellular levels of cyclic adenosine monophosphate (cAMP). cAMP is a derivative of adenosine triphosphate (ATP), many different organisms use cAMP as part of intracellular signal transduction and interplay between potassium, cAMP signaling, PKA, aquaporin regulation and cell water permeability has been reported in mammalian astrocyte cells (Song and Gunnarson, 2012).