Human Gastric intrinsic factor (GIF) is an intrinsic factor of the eukaryotic cobalamin family. Gastric intrinsic factor is a 44 kDa protein containing 380 amino acid residues. It is secreted from the parietal cells in gastric mucosa. Gastric intrinsic factor plays a major role in absorption and transportation of cobalamin and Cbl. It could form the comprised with Vit.B12 that avoid the destroy of Vit.B12.