Enables ammonium transmembrane transporter activity. Involved in ammonium transmembrane transport. Located in apical plasma membrane; basolateral plasma membrane; and cytoplasmic vesicle. Biomarker of hypokalemia; kidney failure; and metabolic acidosis. Orthologous to human RHCG (Rh family C glycoprotein). [provided by Alliance of Genome Resources, Apr 2022]