Reactome | TCN2 binds RCbl in the circulation

TCN2 binds RCbl in the circulation

Stable Identifier

R-HSA-3000074

Type

Reaction [transition]

Species

Homo sapiens

Compartment

extracellular region

Synonyms

TCII binds RCbl in the circulation

ReviewStatus

5/5

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Transcobalamin (TCN2, TC) is secreted by endothelial cells into plasma where it binds cobalamins (RCbl) and mediates their uptake into cells throughout the body. TCN1 (aka haptocorrin) is also present in the blood and binds RCbl efficiently (Johnston et al. 1989, Quadros et al. 1986, Wuerges et al. 2006), but the TCN1:RCbl complex is not readily taken up from the blood by most cells and and Alam et al. (2016) have suggested that the physiological role of TCN1 is to bind and sequester Cbl-like corenoids to prevent their tissue uptake.

Literature References

PubMed ID	Title	Journal	Year
2777761	Structure of the cDNA encoding transcobalamin I, a neutrophil granule protein Berliner, N, Johnston, J, Bollekens, J, Allen, RH	J. Biol. Chem.	1989
3782074	Purification and molecular characterization of human transcobalamin II Rothenberg, SP, Pan, YC, Quadros, EV, Stein, S	J. Biol. Chem.	1986
27411955	Structural basis of transcobalamin recognition by human CD320 receptor Zenobi, R, Alam, A, Prinz, B, Locher, KP, Bloch, JS, Woo, JS, Chen, F, Schmitz, J, Root, K	Nat Commun	2016
16537422	Structural basis for mammalian vitamin B12 transport by transcobalamin Randaccio, L, Wuerges, J, Petersen, TE, Geremia, S, Fedosov, SN, Garau, G	Proc. Natl. Acad. Sci. U.S.A.	2006