High serum vitamin B12 levels are in many cases the result of abnormalities of vitamin B12 transport proteins (
transcobalamins).
Plasma transcobalamins in haematological disorders.
Vitamin [B.sub.12] in serum is bound to 2 proteins, transcobalamin (TC) (3) II and haptocorrin (HC).
The cobalamin-binding proteins transcobalamin and haptocorrin in maternal and cord blood sera at birth.
The vitamin is well retained in plasma and cells due to binding to specific proteins called
transcobalamins or to B12-dependent enzymes, and unlike with most B vitamins, there are minimal losses of B12 in urine.
Levels of transcobalamins I, II, and III during pregnancy and in cord blood.
Vitamin [B.sub.12] (Cobalamin) circulates in plasma bound to 2 carrier proteins, transcobalamin [(TC).sup.4] and haptocorrin (HC).
Homocysteine, folate, vitamin [B.sub.12], and
transcobalamins in patients undergoing successive hypo- and hyperthyroid states [Letter].
Transcobalamins I and II as natural transport proteins of vitamin B12.
Among the few known nonmalabsorptive causes of low cobalamin concentrations is hereditary absence of transcobalamin I/haptocorrin (TC I/HC) [1,2] (11-16), which causes low serum cobalamin concentrations because most cobalamin circulates in the blood attached to TC I/HC (17-19).
Levels in normal, pathological, and foetal sera of the three transcobalamins. Ir J Med Sci 1973;142:51-7.
The unsaturated haptocorrin binding capacity was analyzed, and the unsaturated transcobalamin binding capacity was calculated by subtracting the unsaturated haptocorrin binding capacity from UBBC.
