Transcobalamin receptor (TCblR)

The Transcobalamin receptor (TCblR/CD320) is a type I transmembrane glycoprotein crucial to mammalian cellular uptake of vitamin B12 (cobalamin). It specifically binds the transcobalamin–B12 complex on the cell surface and internalizes it via endocytosis, enabling delivery of this essential vitamin for DNA synthesis, methylation, red blood cell formation, and normal neurological function. TCblR expression is cell cycle regulated, with highest levels in proliferative tissues. Loss-of-function mutations or acquired defects result in B12 deficiency, with corresponding hematologic and neuropsychiatric sequelae. The transporter is also investigated as a target for B12-drug conjugate delivery, particularly in oncology, due to upregulation in some cancer cells. No direct small-molecule modulators are in clinical use, but the pathway is a focus for diagnostic and targeted drug strategies.

Other names

CD320Transcobalamin receptorTCblRCellular cobalamin transporter

Receptor-mediated endocytosis of the transcobalamin-cobalamin (TC-Cbl) complex; Uptake regulated via cell cycle and proliferation state (higher in rapidly dividing cells)