Functions as a specific ammonium transporter. Interacts (via C-terminus) with ANK2 and ANK3; required for targeting to the basolateral membrane. Expressed in kidney by connecting segments and collecting tubules. Also expressed in liver by perivenous hepatocytes. Expressed in the forestomach and the fundus of the stomach. Expressed in duodenum, jejunum, ileum and colon at the level of villous (at protein level). Specifically expressed in kidney where it is restricted to the epithelial linings of the convoluted tubules and the loop of Henle. Also detected in ovary. Expressed by hepatocytes and dermal hair follicles and papillae. Detected in embryos at 15 dpc and 17 dpc. Expressed in kidney, skin and liver of 16.5 dpc embryos. N-glycosylated. Belongs to the ammonium transporter (TC 2.A.49) family. Rh subfamily.