Functions both as a transporter that mediates electroneutral anion exchange across the cell membrane and as a structural protein (PubMed:10926824, PubMed:14734552, PubMed:1538405, PubMed:16227998, PubMed:20151848, PubMed:24121512, PubMed:28387307, PubMed:35835865). Component of the ankyrin-1 complex of the erythrocyte membrane; required for normal flexibility and stability of the erythrocyte membrane and for normal erythrocyte shape via the interactions of its cytoplasmic domain with cytoskeletal proteins, glycolytic enzymes, and hemoglobin (PubMed:1538405, PubMed:20151848, PubMed:35835865). Functions as a transporter that mediates the 1:1 exchange of inorganic anions across the erythrocyte membrane. Mediates chloride-bicarbonate exchange in the kidney, and is required for normal acidification of the urine (PubMed:10926824, PubMed:14734552, PubMed:16227998, PubMed:24121512, PubMed:28387307). {ECO:0000269|PubMed:10926824, ECO:0000269|PubMed:14734552, ECO:0000269|PubMed:1538405, ECO:0000269|PubMed:16227998, ECO:0000269|PubMed:20151848, ECO:0000269|PubMed:24121512, ECO:0000269|PubMed:28387307, ECO:0000269|PubMed:35835865}. (Microbial infection) Acts as a receptor for P.falciparum (isolate 3D7) MSP9 and thus, facilitates merozoite invasion of erythrocytes (PubMed:14630931). Acts as a receptor for P.falciparum (isolate 3D7) MSP1 and thus, facilitates merozoite invasion of erythrocytes (PubMed:12692305). {ECO:0000269|PubMed:12692305, ECO:0000269|PubMed:14630931}. This is the function of SLC4A1 (solute carrier family 4 member 1 (Diego blood group), Ensembl gene identifier ENSG00000004939).