intrinsic factor; gastric intrinsic factor; IF; INF (GIF, IFMH)

Function

• binds to cobalamin (vit B12) & serves as a ligand for a specific receptor in the mucosal brush border of the ileum; promotes absorption cobalamin by receptor-mediated endocytosis
• cobalamin/intrinsic factor complex is resistant to proteolytic digestion

Structure

• belongs to the eukaryotic cobalamin transport proteins family

Compartment

secreted

Expression

• gastric mucosa
• produced by parietal cells of the stomach
• secretion of intrinsic factor parallels that of HCl
• secretion of vit B12 is inhibited by proton pump inhibitors (clinical significance unknown)

Pathology

• deficiency of intrinsic factor gives rise to vitamin B12 deficiency (pernicious anemia)
• defects in the gene for intrinsic factor (GIF) are the cause of congenital pernicious anemia

More general terms

• secreted protein
• mucoprotein

Additional terms

• anti-intrinsic factor antibody (INTRINS)
• cobalamin-binding protein
• pernicious anemia; autoimmune gastritis
• vitamin B12 deficiency
• vitamin B12; cobalamin

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=2694
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:2694
• OMIM: https://mirror.omim.org/entry/261000
• OMIM: https://mirror.omim.org/entry/609342
• UniProt: http://www.uniprot.org/uniprot/P27352.html