GIF gene is a member of the cobalamin transport protein family. It encodes a glycoprotein secreted by parietal cells of the gastric mucosa and is required for adequate absorption of vitamin B12. Vitamin B12 is necessary for erythrocyte maturation and mutations in GIF gene may lead to congenital pernicious anemia. [provided by RefSeq, Jul 2008]
OMIM-Description for Gastric intrinsic factor / GIFN
Gastric intrinsic factor / GIF
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 later on in the small intestine. In humans, the gastric intrinsic factor protein is encoded by the GIF gene. Upon entry into the stomach, vitamin B12 becomes bound to haptocorrin (R factor), a glycoprotein. The resulting complex enters the duodenum, where pancreatic enzymes digest haptocorrin. In the less acidic environment of the small intestine, B12 can then bind to intrinsic factor. This new complex travels to the ileum, where special epithelial cells endocytose them. Inside the cell, B12 dissociates once again and binds to another protein, transcobalamin II. The new complex can exit the epithelial cells to enter the liver.
Belongs to the eukaryotic cobalamin transport proteins family.
Interacts with CUBN (via CUB domains).
Involvement in disease
Hereditary intrinsic factor deficiency (IFD) [MIM:261000]: Autosomal recessive disorder characterized by megaloblastic anemia. Note=The disease is caused by mutations affecting the gene represented in this entry.
Gastric intrinsic factor promotes absorption of the essential vitamin cobalamin (Cbl) in the ileum. After interaction with CUBN, the GIF-cobalamin complex is internalized via receptor-mediated endocytosis.
Gastric intrinsic factor is involved in vitamin B synthesis