Reactome | TCN1 binds RCbl

TCN1 binds RCbl

Stable Identifier

R-HSA-3132759

Type

Reaction [transition]

Species

Homo sapiens

Compartment

extracellular region

ReviewStatus

5/5

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Cobalamins in a +3 oxidation state and with various R groups (collectively, RCbl) are present in the diet as free molecules or complexed with dietary protein. The glycoprotein transcobalamin 1 (TCN1 aka haptocorrin, HC, TCII), produced by salivary glands (Morkbak et al. 2007, Wang et al. 2019), binds free RCbl and in the stomach binds RCbl freed by the initial digestion of dietary protein. In its complexed form acid-sensitive RCbl is protected from degradation in the stomach (Nielsen et al. 2012) and is available for endocytosis.

Literature References

PubMed ID	Title	Journal	Year
22547309	Vitamin B12 transport from food to the body's cells--a sophisticated, multistep pathway Rasmussen, MR, Moestrup, SK, Andersen, CB, Nielsen, MJ, Nexø, E	Nat Rev Gastroenterol Hepatol	2012
17990953	Haptocorrin in humans Morkbak, AL, Poulsen, SS, Nexo, E	Clin Chem Lab Med	2007
30777892	A deep proteome and transcriptome abundance atlas of 29 healthy human tissues Hallström, B, Gagneur, J, Frejno, M, Hahne, H, Asplund, A, Zolg, DP, Eraslan, B, Kuster, B, Schnatbaum, K, Li, LH, Wieland, T, Hopf, T, Meng, C, Zecha, J, Schmidt, T, Ponten, F, Uhlén, M, Wilhelm, M, Wang, D	Mol Syst Biol	2019