• Purity

  >95%, by SDS-PAGE with silver staining

• Endotoxin Level

  <0.10 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its ability to bind Vitamin B12. The specific binding is  ≥30 μg Vitamin B12/mg Recombinant Human GIF.

• Source

  Human embryonic kidney cell, HEK293-derived Ser19-Tyr417 with a C-terminal 6-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  Ser19

• Predicted Molecular Mass

  44 kDa

• SDS-PAGE

  44-60 kDa, reducing conditions

Background: GIF

Gastric Intrinsic Factor (GIF) also known as Intrinsic Factor (IF) is a 45-55 kDa glycoprotein that is secreted by parietal cells of the gastric mucosa. GIF is a member of the eukaryotic cobalamin (Cbl or Vitamin B12) family of transport proteins that mediate the uptake of cobalamin by intestinal epithelial cells lining the ileum (1). GIF comprises two domains, an alpha and a beta -domain containing approximatively 270 and 110 residues respectively (2). Cobalamin binds to GIF at the interface of the alpha  and beta  domains (2). The Cbl-GIF complex can then interact with its specific receptor, Cubilin, through the amino-terminal portion of GIF (3). This complex associates with Amnionless (AMN) which directs subcellular localization and endocytosis of Cubilin and its ligands (4). Homozygous nonsense and missense mutations in the GIF gene have been linked to hereditary juvenile megaloblastic anemia. These patients show nutritional cobalamin insufficiency due to its intestinal malabsorption (5). Mature human GIF shares 82% and 79% amino acid sequence identity with mouse GIF and rat GIF respectively.

• References:

1. Hewitt, J.E. et al. (1991) Genomics 10:432.

2. Mathews, F.S. et al. (2007) Proc. Natl. Acad. Sci. USA 104:17311.

3. Tang, L-H. et al. (1992) J. Biol. Chem. 267:22982.

4. Fyfe, J.C. et al. (2004) Blood 103:1573.

5. Tanner, S.M. et al. (2005) Proc. Natl. Acad. Sci. USA 102:4130.

• Long Name:

  Gastric Intrinsic Factor

• Entrez Gene IDs:

  2694 (Human); 14603 (Mouse); 29319 (Rat)

• Alternate Names:

  gastric intrinsic factor (vitamin B synthesis); GIF; IF; IFIntrinsic factor; IFMH; IFMHgastric intrinsic factor; INF; TCN3