Electroneutral sodium- and bicarbonate-dependent cotransporter with a Na(+):HCO3(-) 1:1 stoichiometry (PubMed:10347222, PubMed:12403779, PubMed:14578046, PubMed:14736710). Mediates the sodium-dependent bicarbonate transport important for pH recovery after acid load as well as for regulation of steady-state pH in the duodenum and vascular smooth muscle cells (By similarity). Plays a key role in macrophage acidification, mediating bicarbonate import into the cytoplasm which is crucial for net acid extrusion and maintenance of cytoplasmic pH during phagocytosis (PubMed:29779931). Provides cellular bicarbonate for de novo purine and pyrimidine synthesis and is a key mediator of de novo nucleotide synthesis downstream of mTORC1 signaling in proliferating cells (PubMed:35772404). {ECO:0000250|UniProtKB:Q8BTY2, ECO:0000269|PubMed:10347222, ECO:0000269|PubMed:12403779, ECO:0000269|PubMed:14578046, ECO:0000269|PubMed:14736710, ECO:0000269|PubMed:29779931, ECO:0000269|PubMed:35772404}. [Isoform 6]: Plays a key role in macrophage acidification, mediating bicarbonate import into the cytoplasm which is crucial for net acid extrusion and maintenance of cytoplasmic pH during phagocytosis. . This is the function of Ensembl gene identifier ENSG00000033867 (SLC4A7, solute carrier family 4 member 7).