Gastric Intrinsic Factor (GIF)

Gastric intrinsic factor, also known as GIF, belongs to the of the cobalamin transport protein family. It is a glycoprotein produced by the parietal cells of the stomach. Gastric intrinsic factor plays a key role in the absorption of vitamin B12 on in the small intestine. Vitamin B12 bounds to haptocorrin after entry into the stomach. 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 gastric 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.

Gastric Intrinsic Factor (GIF) Alternative Names

IF, IFMH, INF, TCN3, gastric intrinsic factor, intrinsic factor [Homo sapiens]

AV073125, IF, INF, intrinsic factor [Mus musculus]

Summaries for Gastric Intrinsic Factor (GIF)

Entrez Gene summary for Gastric intrinsic factor (GIF):

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]

Wikipedia summary for 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.

Human Gastric Intrinsic Factor (GIF) Protein General Information

 

• Protein names: Gastric intrinsic factor
  Short name=GIF
• Sequence length: 417 AA.
• Domain: Signal
• Sequence similarities: Belongs to the eukaryotic cobalamin transport proteins family.
• Subunit structure: Interacts with CUBN (via CUB domains).
• Subcellular location: Secreted.
• Tissue specificity: Gastric mucosa.
• Involvement in disease: Defects in GIF are the cause of hereditary intrinsic factor deficiency (IFD) ; also known as congenital pernicious anemia. IFD is an autosomal recessive disorder characterized by megaloblastic anemia.

General information above from UniProt

Function for Gastric Intrinsic Factor (GIF) Protein

UniProtKB:

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.

Genatlas:

• Gastric intrinsic factor is involved in vitamin B synthesis

Phenotype Information for Gastric Intrinsic Factor (GIF)

• Gene/Locus: GIF, IF
• Phenotype: Intrinsic factor deficiency

Phenotype Information for Gastric intrinsic factor (GIF) from OMIM (Online Mendelian Inheritance in Man)