Transcobalamin

Called by the human Transcobalaminen also Haptocorrinen or R- binder proteins is a set of transport proteins for vitamin B12 (cobalamin ).

Currently, one distinguishes three transcobalamins: transcobalamin I, II and III.

Transcobalamin I is composed of 433 amino acid protein with a molecular mass of 48,209 daltons, which is encoded on chromosome 11 and migrates during electrophoresis as a beta - globulin. Transcobalamin I is used in the blood to transport " excess " vitamin B12 back to the liver as the storage organ.

Transcobalamin II is composed of 427 amino acid protein with a molecular mass of 47,538 daltons, which is encoded on chromosome 22 and in electrophoresis (as transcobalamin III) as the alpha globulin travels. Transcobalamin II is used for the transport of vitamin B12 to the cells, which can use the Vitamin B12 - transcobalamin complex ( holo - Transcobalamin II or holo-TC II given) record by binding to a membrane receptor (so-called " receptor mediated endocytosis ").

In particular, the inclusion of Holo - transcobalamins II occurs via a special transcobalamin II receptor, which travels along with the vitamin B12 - transcobalamin complex in a "coated vesicle " from the blood into the cell interior, where the transcobalamin II after release of vitamin B12 is transported back into the blood.

For transcobalamin II (chromosome 22q12.2 ) genetic abnormalities are known, which can lead to cellular vitamin B12 deficiency despite normal serum levels, which in turn occur to a number at birth disorders such as anemia (anemia), weakened immune system due to immunoglobulin -G deficiency or various neurological symptoms.