Multidrug efflux pump that functions as a H(+)/organic cation antiporter (, ). Plays a physiological role in the excretion of cationic compounds including endogenous metabolites, drugs, toxins through the kidney and liver, into urine and bile respectively (   , ). Mediates the efflux of endogenous compounds such as creatinine, vitamin B1/thiamine, agmatine and estrone-3-sulfate (   , ). May also contribute to regulate the transport of cationic compounds in testis across the blood-testis-barrier (Probable).
Subcellular locations: Cell membrane, Apical cell membrane
Localizes to the plasma membrane; at the brush border membranes of the proximal tubules (kidney) and at the bile caniculi (liver).
Widely expressed. The highest expression is found in adrenal gland, and to a lower extent in liver, skeletal muscle and kidney. In testis, primarily localized throughout the adluminal compartment of the seminiferous tubules with expression at the peritubular myoid cells and Leydig cells .