Reactome | CD320 binds extracellular TCN2:RCbl

CD320 binds extracellular TCN2:RCbl

Stable Identifier

R-HSA-3000122

Type

Reaction [transition]

Species

Homo sapiens

Compartment

extracellular region, endosome membrane, endosome

ReviewStatus

5/5

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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