Aquaporin-9

Aquaporin-9 (AQP9) is a protein that in humans is encoded by the AQP9 gene. It is a member of the aquaporin family of integral membrane proteins that conduct water and small solutes across the cell membrane.

Function

Aquaporin-9 is a water-selective transporting protein that provides the plasma membranes of hepatocytes and erythrocytes with high permeability to water, helping to facilitate the transport of water and small solutes across cell membranes. It is also permeable to urea and glycerol and may play an important role in glycerol metabolism.

Structure

The AQP9 protein is a member of the larger aquaporin family of proteins, which all share a similar structure. This structure includes six transmembrane domains and five connecting loops, with the N- and C-termini located on the cytoplasmic side of the membrane. The protein forms a tetramer in the membrane, with each monomer functioning as an independent water pore.

Clinical significance

Alterations in the expression of AQP9 have been observed in several diseases, including diabetes mellitus, hepatitis, and cancer. In particular, AQP9 may play a role in the development of insulin resistance in type 2 diabetes.

See also

• Aquaporin
• Aquaglyceroporin

External links

• AQP9 at GeneCards