RHCG (Rh family C glycoprotein) is a polytopic membrane glycoprotein that functions as an ammonium transporter crucial for maintaining acid-base homeostasis 1. The protein is predominantly expressed in kidney collecting tubules and testis seminiferous tubules, with exclusive plasma membrane localization 1. RHCG mediates electroneutral bidirectional transport of NH3 ammonia species through a mechanism involving NH4+ interaction with acidic residues, followed by dissociation into NH3 and H+, with NH3 transiting through the central pore 2. Additionally, RHCG demonstrates significant CO2 permeability, potentially contributing to renal acid secretion 2. In human kidney, RHCG is the major putative ammonia transporter, with both apical and basolateral localization in distal convoluted tubule and intercalated cells 3. Functional studies demonstrate that RhCG deficiency severely reduces renal ammonium secretion and causes metabolic acidosis in acid-challenged conditions 4. Beyond its physiological role, RHCG shows clinical significance in disease contexts, being highly expressed in endometrial cancer where it promotes malignant proliferation and migration while conferring anti-apoptotic activity 5. The protein has also been identified in psoriasis pathogenesis, where it associates with keratinocyte differentiation and DC cell maturation 6.