Functions as a highly-selective sodium transporter (PubMed:19482918, PubMed:25750424). Does not seem to function as sodium-potassium cotransporter (PubMed:19482918, PubMed:25750424). May be involved in turgor changes for rolling and unrolling of leaves in response to environmental variations (PubMed:19482918). Na(+)(in) = Na(+)(out) Interacts with CNIH1. Weakly expressed (PubMed:12795699). In roots, expressed in epidermis, exodermis, cortex, and sieve elements and companion cells of phloem (PubMed:19482918). In mature leaves, expressed in large highly vacuolated cells of the adaxial epidermis, phloem and xylem (PubMed:19482918). HKT transporters are proposed to contain 4 pore-forming regions enclosed by transmembrane segments with each containing a potassium channel-like selectivity filter motif. Belongs to the TrkH potassium transport family. HKT (TC 2.A.38.3) subfamily.