Serine/threonine-protein kinase which is involved in the regulation of a wide variety of ion channels, membrane transporters, cell growth, survival and proliferation. Up-regulates Na(+) channels: SCNN1A/ENAC, K(+) channels: KCNA3/Kv1.3, KCNE1 and KCNQ1, amino acid transporter: SLC6A19, glutamate transporter: SLC1A6/EAAT4, glutamate receptors: GRIA1/GLUR1 and GRIK2/GLUR6, Na(+)/H(+) exchanger: SLC9A3/NHE3, and the Na(+)/K(+) ATPase. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Two specific sites, one in the kinase domain (Thr-193) and the other in the C-terminal regulatory region (Ser-356), need to be phosphorylated for its full activation. Expressed in the proximal tubule and thick ascending limb of the loop of Henle (TALH). Activated by phosphorylation on Ser-356 by an unknown kinase (may be mTORC2 but not confirmed), transforming it into a substrate for PDPK1 which then phosphorylates it on Thr-193. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family.