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Intrinsic Factor

Intrinsic factor (IF), cobalamin binding intrinsic factor, also known as gastric intrinsic factor (GIF), is a glycoprotein produced by the parietal cells (in humans) or chief cells (in rodents) of the stomach. It is necessary for the absorption of vitamin B12 later on in the distal ileum of the small intestine. In humans, the gastric intrinsic factor protein is encoded by the CBLIF gene. Haptocorrin (transcobalamin I) is another glycoprotein secreted by the salivary glands which binds to vitamin B12. Vitamin B12 is acid-sensitive and in binding to haptocorrin it can safely pass through the acidic stomach to the duodenum.In the less acidic environment of the small intestine, pancreatic enzymes digest the glycoprotein carrier and vitamin B12 can then bind to in… more »