Component of the ankyrin-1 complex, a multiprotein complex involved in the stability and shape of the erythrocyte membrane (PubMed:35835865). Heterotrimer with RHCE (RHAG)2(RHCE), that transports ammonium and its related derivative methylammonium, in both neutral and ionic forms, across the erythrocyte membrane (PubMed:11062476, PubMed:11861637, PubMed:15572441, PubMed:15856280, PubMed:19273840, PubMed:21849667, PubMed:22012326, PubMed:24077989, PubMed:26354748). The transport of NH4(+) is electrogenic and masks the NH3 transport (PubMed:26354748). Also, may act as a CO2 channel (PubMed:17712059, PubMed:19273840, PubMed:24077989). In vitro, leaks monovalent cations (PubMed:18931342, PubMed:21849667). Moreover in erythrocyte, regulates RHD membrane expression (PubMed:12130520) and is associated with rhesus blood group antigen expression (PubMed:12130520, PubMed:19744193). {ECO:0000269|PubMed:11062476, ECO:0000269|PubMed:11861637, ECO:0000269|PubMed:12130520, ECO:0000269|PubMed:15572441, ECO:0000269|PubMed:15856280, ECO:0000269|PubMed:17712059, ECO:0000269|PubMed:18931342, ECO:0000269|PubMed:19273840, ECO:0000269|PubMed:19744193, ECO:0000269|PubMed:21849667, ECO:0000269|PubMed:22012326, ECO:0000269|PubMed:24077989, ECO:0000269|PubMed:26354748, ECO:0000269|PubMed:35835865}. This is the function of ENSG00000112077 (RHAG, Rh associated glycoprotein).