Low-affinity potassium transport system. Interacts with Trk system potassium uptake protein TrkA. Requires TrkE (sapD) for transport activity, 20% more uptake is seen with both SapD and SapF (PubMed:11700350). Transport in the absence of SapD and SapF is dependent on a high membrane potential and a high cytoplasmic ATP concentration, suggesting this protein may be able to interact with other ATP-binding proteins (PubMed:11700350). Can transport potassium and rubidium (PubMed:7896723). Belongs to the TrkH potassium transport family.