Serine/threonine-protein kinase which phosphorylates gck-3 (PubMed:18049475). Plays a role in osmotic stress responses during which it increases gpdh-1 translation, likely by phosphorylating gck-3 (PubMed:23076791). Essential for larval development and the tubular formation of the excretory canals (PubMed:18049475). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with gck-3 (via C-terminus). Expressed in pharynx, nervous system, hypodermis, spermatheca, excretory cell and canal and body wall muscles. RNAi-mediated knockdown causes impaired survival and slower volume recovery upon hypertonic stress. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. WNK subfamily. Was named WNK/'with no lysine(K)' because key residues for catalysis, including the lysine involved in ATP binding, are either not conserved or differ compared to the residues described in other kinase family proteins.