Haptocorrin often known as transcobalamin-1 (TC-1) or cobalophilin is a transcobalamin protein that in people is encoded by the TCN1 gene. The important perform of haptocorrin is safety of the acid-sensitive vitamin B12 whereas it strikes by the abdomen.
Haptocorrin (HC), additionally generally referred to as the R-protein, or the R-factor, or beforehand known as transcobalamin I, is a singular glycoprotein produced by the salivary glands of the oral cavity, in response to ingestion of meals. This protein binds strongly to vitamin B12 in what’s an intricate and vital mechanism to guard this vitamin from the acidic surroundings of the abdomen.:44 Vitamin B12 is an important water-soluble vitamin, the deficiency of which creates anemia (macrocytic anemia), decreased bone marrow cell manufacturing (anemia, pancytopenia), neurological issues, in addition to metabolic points (methylmalonyl-CoA acidosis).:50–51
Vitamin B12 is subsequently an essential vitamin for the physique to soak up. Regardless of its very important function nevertheless, vitamin B12 is structurally very delicate to the hydrochloric acid discovered within the abdomen secretions, and simply denatures in that surroundings earlier than it has an opportunity to be absorbed by the small gut. Present in recent animal merchandise (corresponding to liver), vitamin B12 attaches haptocorrin, which has a excessive affinity for its molecular construction. Coupled collectively vitamin B12 and haptocorrin create a posh. This haptocorrin–B12 advanced is impervious to the insult of the abdomen acid, and passes on by way of the pylorus to the duodenum. Within the duodenum pancreatic proteases (a part of pancreatic juice) cleave haptocorrin, releasing vitamin B12 in its free kind.
The identical cells within the abdomen that produce gastric hydrochloric acid, the parietal cells, additionally produce a molecule known as the intrinsic issue (IF), which binds the B12 after its launch from haptocorrin by digestion, and with out which just one% of vitamin B12 is absorbed. Intrinsic issue (IF) is a glycoprotein, with a molecular weight of 45 kDa. Within the duodenum, the free vitamin B12 attaches to the intrinsic issue (IF) to create a vitamin B12–IF advanced. This advanced then travels by the small bowel and reaches the terminal tertiary portion of the small gut, known as the ileum. The ileum is the longest of all parts of the small gut, and has on its floor specialised receptors known as cubilin receptors, that determine the B12–IF complexes and take them up into the circulation by way of endocytosis-mediated absorption.
In brief, the important perform of haptocorrin is safety of the acid-sensitive vitamin B12 whereas it strikes by the abdomen.
Haptocorrin additionally circulates and binds roughly 80% of circulating B12, rendering it unavailable for mobile supply by transcobalamin II.
– “r protein b12”
“r protein b12”