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] Interacts with sty1. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.