Promotes K(+) uptake, by the potassium transporter TRK1-TRK2, which leads to the subsequent cellular resistance to toxic cations such as Na(+), Li(+) and Ca(2+). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Present with 1030 molecules/cell in log phase SD medium. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.