Aquaporin-8 is a protein that in humans is encoded by the AQP8 gene. Aquaporin 8 (AQP8) is a water channel protein. Aquaporins are a family of small integral membrane proteins related to the major intrinsic protein (MIP or AQP0). Aquaporin 8 mRNA is found in pancreas and colon but not other tissues. Forms a water-specific channel; mercury-sensitive. Not permeable to glycerol or urea. Expressed only in pancreas and colon.