Intrinsic Factor

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.

Read more about Intrinsic Factor:  Site of Secretion, Clinical Significance, Treatment, Model Organisms

Other articles related to "intrinsic, intrinsic factor":

Schilling Test - Complications
... repletion and correction of the anemia, and it will still show if the cause of the B deficiency was intrinsic-factor related ... with intestinal cell function, and thus cause malabsorption of B on their own, even if intrinsic factor is being made ... state would then tend to cause a false-positive test for both simple B and intrinsic factor-related B malabsorption ...
Intrinsic Factor - Model Organisms
... Gif knockout mouse phenotype Characteristic Phenotype Homozygote viability Normal Homozygous Fertility Abnormal General Observations Abnormal Body weight Normal Anxiety Normal Neurological assessment Normal Grip strength Normal Hot plate Normal Dysmorphology Normal Indirect calorimetry Normal Glucose tolerance test Normal Auditory brainstem response Normal DEXA Normal Radiography Normal Body temperature Normal Eye morphology Normal Clinical chemistry Normal Plasma immunoglobulins Normal Haematology Normal Peripheral blood lymphocytes Normal Micronucleus test Normal Heart weight Normal Tail epidermis wholemount Normal Skin Histopathology Normal Brain histopathology Normal MicroCT Quantitative Faxitron Normal Salmonella infection Abnormal Citrobacter infection Abnormal All tests and analysis from Model organisms have been used in the study of intrinsic factor function ... A conditional knockout mouse line, called Giftm1a(KOMP)Wtsi was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists ...
Hydroxocobalamin - Causes of Deficiency
... of vitamin B12 resulting from structural or functional damage to the stomach where intrinsic factor is secreted or to the ileum where intrinsic factor facilitates vitamin B12 ...
Vitamin B12
... which parietal cells of the stomach responsible for secreting intrinsic factor are destroyed ... Intrinsic factor is crucial for the normal absorption of B12, so a lack of intrinsic factor, as seen in pernicious anemia, causes a vitamin B12 deficiency ...
Anaemic - Classification - Production Vs. Destruction or Loss - Macrocytic
... Pernicious anemia is caused by a lack of intrinsic factor, which is required to absorb vitamin B12 from food ... A lack of intrinsic factor may arise from an autoimmune condition targeting the parietal cells (atrophic gastritis) that produce intrinsic factor or ...

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