Haptocorrin

Haptocorrin (also known as HC, R-factor, or transcobalamin I) is a glycoprotein that binds to vitamin B12 and carries it through the stomach and into the intestine. It is one of three proteins, along with intrinsic factor and transcobalamin, that bind to vitamin B12, but it is unique in that it is resistant to acid and proteolysis in the stomach.

Function

Haptocorrin is produced in the salivary glands and is secreted into the saliva. It binds to vitamin B12 as soon as it enters the mouth, protecting it from the acidic environment of the stomach. Once in the intestine, the vitamin B12 is released from the haptocorrin and is then bound by intrinsic factor, which facilitates its absorption by the enterocytes.

Clinical significance

Haptocorrin levels can be measured in the blood and can be used as a marker for certain diseases. Low levels of haptocorrin can indicate a deficiency in vitamin B12, while high levels can indicate a number of conditions, including liver disease, kidney disease, and certain types of cancer.

See also

• Vitamin B12
• Intrinsic factor
• Transcobalamin

References

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