WNK4 binds and phosphorylates claudins 1–4.
Claudins 1–4 are known to be involved in the regulation of paracellular ion permeability.
The increases in phosphorylation of claudins were greater in cells expressing the mutant WNK4 than in cells expressing wild-type protein.
Disease-causing mutant WNK4 increases paracellular chloride permeability and phosphorylates claudins.
So the phosphorylation of Claudins 1-4 by WNK4 involves in the regulation of paracellular ion permeability