This protein family consists of various potassium transport proteins (Trk) and V-type sodium ATP synthase subunit J or translocating ATPase J (EC).

These proteins are involved in active sodium uptake utilizing ATP in the process.

TrkH from Escherichia coli is a transmembrane protein and determines the specificity and kinetics of cation transport by the TrK system in this organism.

[1] This protein interacts with TrkA and requires TrkE for transport activity.