Vitamin B12 transporters (B12T)

Vitamin B12 transporters are a specialized group of proteins, including Gastric intrinsic factor (GIF), Cubilin (CUBN), and the Transcobalamin receptor (CD320), which collectively manage the absorption and cellular entry of cobalamin (Vitamin B12). In the gastrointestinal tract, B12 binds to GIF and is recognized by the Cubilin-Amnionless complex in the ileum for internalization (PMID: 11134015). Once in the bloodstream, B12 is carried by Transcobalamin II (TCN2) and enters peripheral cells via CD320-mediated endocytosis (PMID: 18779389). These transporters are significant therapeutic targets because they can be leveraged for the oral delivery of large molecules, such as insulin or GLP-1 analogs, by conjugating them to B12 to exploit the natural uptake pathway (PMID: 22403342). Furthermore, the overexpression of CD320 in various malignancies makes it a candidate for targeted delivery of cytotoxic agents and radiopharmaceuticals (PMID: 25130395). Dysfunctions in these transporters are linked to clinical conditions such as megaloblastic anemia and various neurodegenerative symptoms due to impaired DNA synthesis and myelin maintenance (StatPearls: NBK441923). The system's high specificity and efficiency in transporting cobalamin make it an attractive platform for overcoming biological barriers in drug development.

Other names

Cobalamin transportersCD320Transcobalamin receptorTCblRCubilin-amnionless complexIntrinsic factor receptorCUBNTCN2Gastric intrinsic factor

Facilitation of Vitamin B12 (cobalamin) absorption and cellular entry through high-affinity binding and receptor-mediated endocytosis.