Two diseases caused by intrinsic factor
Answers
Intrinsic factor (IF), also known as gastric intrinsic factor (GIF), is a glycoprotein produced by the parietal cells of the stomach. It is necessary for the absorption of vitamin B12 (cobalamin) later on in the ileum of the small intestine.[5] In humans, the gastric intrinsic factor protein is encoded by the GIF gene.[6]:989
Haptocorrin (also known as HC, R protein, and transcobalamin I, TCN1) is another glycoprotein secreted by the salivary glands which binds to vitamin B12. Vitamin B12 is acid sensitive and in binding to transcobalamin I it can safely pass through the acidic stomach to the duodenum.[7] In the less acidic environment of the small intestine, pancreatic enzymes digest the glycoprotein carrier and vitamin B12 can then bind to intrinsic factor.[7] This new complex is then absorbed by the epithelial cells (enterocytes) of the ileum.[7] Inside the cells, B12 dissociates once again and binds to another protein, transcobalamin II (TCN2); the new complex can then exit the epithelial cells to be carried to the liver.