Component of the ankyrin-1 complex, a multiprotein complex involved in the stability and shape of the erythrocyte membrane . Heterotrimer with RHCE (RHAG)2(RHCE), that transports ammonium and its related derivative methylammonium, in both neutral and ionic forms, across the erythrocyte membrane (    ). The transport of NH4(+) is electrogenic and masks the NH3 transport . Also, may act as a CO2 channel ( ). In vitro, leaks monovalent cations (, ). Moreover in erythrocyte, regulates RHD membrane expression  and is associated with rhesus blood group antigen expression (, ).
Subcellular locations: Membrane
Localization at the plasma membrane is regulated by ANK1.
Erythrocytes.