CD320 binds extracellular TCN2:RCbl

Stable Identifier
Reaction [transition]
Homo sapiens
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The ubiquitously expressed CD320 antigen (CD320 aka transcobalamin receptor, TCblR) internalises TCN2:RCbl, enabling uptake of cobalamins (RCbl) from the blood by cells throughout the body (Quadros et al. 2009, Quadros et al. 2005). Defects in CD320 cause methylmalonic aciduria type TCblR (MMATC aka methylmalonic aciduria; MIM:613646) (Quadros et al. 2010). The first patient identified had only methylmalonic aciduria, subsequent patients had both this and homocystinuria. There is so far no confirmed clinical consequence of this disorder; patients have somewhat elevated MMA and homocysteine levels but no consistent additional findings.
Literature References
PubMed ID Title Journal Year
15652495 The binding properties of the human receptor for the cellular uptake of vitamin B12

Nakayama, Y, Quadros, EV, Sequeira, JM

Biochem. Biophys. Res. Commun. 2005
18779389 The protein and the gene encoding the receptor for the cellular uptake of transcobalamin-bound cobalamin

Nakayama, Y, Quadros, EV, Sequeira, JM

Blood 2009
20524213 Positive newborn screen for methylmalonic aciduria identifies the first mutation in TCblR/CD320, the gene for cellular uptake of transcobalamin-bound vitamin B(12)

Lai, SC, Gallagher, RC, Wright, E, Quadros, EV, Rosenblatt, DS, Fedosov, S, Wang, S, Watkins, D, Hannibal, L, Nakayama, Y, Sequeira, JM, Anastasio, N, Jacobsen, DW

Hum. Mutat. 2010
Catalyst Activity

cargo receptor activity of CD320 [plasma membrane]

Orthologous Events
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