Involved in trafficking to the vacuole (PubMed:21278129). Required for cell proliferation and cell expansion, but not for cell differentiation (PubMed:21278129). Acts in low affinity electroneutral exchange of protons for cations such as Na(+) or K(+) across membranes (PubMed:12047628). May also exchange Li(+) and Cs(+) with a lower affinity (By similarity). H(+)(out) + Na(+)(in) = H(+)(in) + Na(+)(out) H(+)(out) + K(+)(in) = H(+)(in) + K(+)(out) Expressed in roots, leaves, stems, flowers and siliques. Detected at low levels in roots and shoots. Induced by NaCl in a ABA-independent manner. No visible phenotype; due to redundancy with NHX6. Nhx5 and nhx6 double mutant has a slower development, is drastically smaller and is salt sensitive. Belongs to the monovalent cation:proton antiporter 1 (CPA1) transporter (TC 2.A.36) family.