What is the role of transcobalamin 2?
The TCN2 gene provides instructions for making a protein called transcobalamin (formerly known as transcobalamin II). This protein transports cobalamin (also known as vitamin B12) from the bloodstream to cells throughout the body.
What is the role of Transcobalamin II in vitamin B12 metabolism?
The IF‐vitamin B12 complex is absorbed via the IF‐B12 receptor, and vitamin B12 is subsequently bound to transcobalamin II (TC II) and released into the circulation. TC II facilitates the transport of vitamin B12 in blood to various tissues.
What causes transcobalamin deficiency?
Mutations in the TCN2 gene cause transcobalamin deficiency. The TCN2 gene provides instructions for making a protein called transcobalamin. This protein attaches (binds) to cobalamin and transports the vitamin to cells throughout the body.
What is Transcobalamin II deficiency?
Transcobalamin II deficiency is a rare autosomal recessive disorder causing intracellular cobalamin depletion, which in turn causes megaloblastic bone marrow failure, accumulation of homocysteine and methylmalonic acid with clinical findings of failure to thrive, diarrhea, vomiting, pancytopenia, megaloblastic anemia.
What is Adenosylcobalamin good for?
Adenosylcobalamin is an active form of vitamin B12, a water-soluble vitamin used as a nutritional supplement to treat vitamin B12 deficiency or pernicious anemia, stomatitis, as well as for other conditions like depression, panic attacks and anxiety. Adenosylcobalamin is also known as cobamide or dibencozide.
Is Transcobalamin a transport protein?
Transcobalamins I and II as natural transport proteins of vitamin B12.
How is Transcobalamin deficiency diagnosed?
Diagnosis of TC deficiency is suspected based on megaloblastic anemia, elevation of total plasma homocysteine, and blood or urine methylmalonic acid. It is confirmed by studying the synthesis of TC in cultured fibroblasts, or by molecular analysis of the TCN2 gene.
What protein is needed for vitamin B12 absorption in the intestine?
intrinsic factor
Normally, vitamin B12 is readily absorbed in the last part of the small intestine (ileum), which leads to the large intestine. However, to be absorbed, the vitamin must combine with intrinsic factor, a protein produced in the stomach.
Is adenosylcobalamin methylated?
Cyanobalamin: synthetic version; used least efficiently by the body. Methylcobalamin: an active form (meaning, ready to be used by the body) of B12 that supports the methylation process. Adenosylcobalamin: another active form of B12 that primarily supports mitochondrial function and metabolism.
Is adenosylcobalamin natural?
Adenosylcobalamin is the natural, most common form of vitamin B12 found in the cells, organs, and tissues of the human body, as well as the most common form of B12 found in food.
What is R binder?
R binders (cobalophilins) are proteins present in saliva that bind dietary cobalamin. • Pancreatic enzymes cleave cobalamin from R binders in duodenum. • Free cobalamin then binds to intrinsic factor, which is secreted by gastric parietal cells.
What is transcobalamin II deficiency?
Transcobalamin II (TCII) deficiency is an autosomal recessive disease marked by defective intestinal absorption of vitamin B12. Homozygous TCII deficiency causes non-specific symptoms in one- and two-month-old infants (e.g. vomiting, poor growth) and infections due to an immune deficiency (hypogammaglobulinemia).
What is the function of cobalamin?
Cobalamin transport proteins and their cell-surface receptors The primary function of cobalamin (Cbl; vitamin B12) is the formation of red blood cells and the maintenance of a healthy nervous system.
What is the role of LRP2 and TCII in cobalamin–TCII complex uptake?
The tissular cobalamin–TCII complex uptake is achieved through megalin (LRP2) and transcobalamin II receptor (TCII-R)-mediated endocytosis, which plays a crucial role in cobalamin homeostasis. It is worth mentioning that TCII is responsible for the cellular uptake of vitamin B12 in most tissues and that TC deficiency is associated with severe MGA.
What is the optimal serum cobalamin level for TC II deficiency?
Serum cobalamin levels must be kept very high (1,000–10,000 pg/ml) in order to treat TC II deficiency patients successfully.