Aquaporin-9 (AQP9)

Aquaporin-9 is a membrane channel protein encoded by the AQP9 gene in humans. It belongs to the aquaglyceroporin subfamily within the major intrinsic protein family. Unlike classical aquaporins that primarily conduct water, Aquaporin-9 facilitates the passage of a broad range of noncharged solutes including glycerol, urea, lactate, purines, pyrimidines, arsenite, and possibly ammonium. It forms homotetrameric channels in cell membranes—each monomer acting independently—and is especially important for hepatic uptake of glycerol supporting gluconeogenesis. In addition to its metabolic roles in liver cells (hepatocytes), it may participate in specialized functions such as immunological responses by leukocytes and protection against arsenic toxicity through excretion pathways. The structure features six transmembrane domains with intracellular N- and C-termini typical for aquaporins.

Other names

AQP-9Aquaglyceroporin 9Major intrinsic protein 9 (less common)

Potential mechanisms for future drugs could include inhibition or modulation of channel activity to alter water/glycerol/solute flux across membranes.