Retinol-binding protein

Retinol-binding protein (RBP) is a protein that in humans is encoded by the RBP1 gene. It is a member of the lipocalin family of proteins, which transport small hydrophobic molecules such as lipids and steroids. RBP specifically binds to retinol (Vitamin A), and transports it from the liver to peripheral tissues.

Function

Retinol-binding protein is the primary transporter of retinol to tissues outside the liver. It binds retinol and retinyl esters, and delivers them to target cells where they are metabolized. This is essential for vision, immune system function, and cellular differentiation.

Structure

RBP is a single-chain polypeptide with a molecular weight of approximately 21,000 daltons. It has a barrel-like structure with a hydrophobic interior that binds to retinol. The protein is stabilized by a disulfide bond.

Clinical significance

Alterations in the level of RBP can indicate vitamin A deficiency or malnutrition. High levels of RBP in the urine can indicate kidney disease. Mutations in the RBP1 gene can cause retinitis pigmentosa, a group of genetic disorders that lead to progressive loss of vision.

See also

• Retinol
• Vitamin A
• Lipocalin
• Retinitis pigmentosa

References

• 
  Retinol-binding protein