Transcobalamin II receptor (TCblR (also known as CD320))

The transcobalamin II receptor (TCblR, CD320) is a glycosylated cell surface receptor essential for cellular uptake of vitamin B12 (cobalamin) in complex with its carrier transcobalamin II. TCblR belongs to the low-density lipoprotein receptor (LDLR) family and specifically recognizes the transcobalamin-cobalamin complex on the plasma membrane, internalizing it through endocytosis. The receptor contains two LDL receptor class A domains and is heavily glycosylated, with a mature protein size of 58–62 kDa. Its gene, CD320, is located on chromosome 19p13.2. TCblR is expressed at higher levels in rapidly proliferating cells to meet increased vitamin B12 demand, making it relevant in cancer biology. Defects or deficiencies in this receptor impair cellular B12 uptake, leading to megaloblastic anemia and neurological disorders. While direct pharmacological targeting is still experimental, TCblR has attracted attention for targeted drug delivery using vitamin B12 conjugates due to its efficient and specific cellular uptake pathway[3][1][5][8].

Other names

CD320TCII receptorTCblRhuman transcobalamin receptortranscobalamin II receptor

Mediates internalization of transcobalamin-cobalamin complex into cells via receptor-mediated endocytosis[3][1]. Experimental antibody-drug conjugates or B12-drug bioconjugates use TCblR-mediated uptake for targeted delivery to specific cells[7][4].