The function of integral membrane protein is crucial for many important biological processes in the cell. These proteins serve as sensors for changes in the extracellular milieu and are involved in signal transduction through the membrane. They also function as channels by controlling or facilitating the transport of ions, water and other substances in or out of the cell. Membrane proteins are often targets for drug development because of their central role in the cells and information about their three dimensional structure is a very important tool for understanding their function in different biological processes at a molecular level. Aquaporins are passive channels that are found in biological membranes in all organisms. They have highly conserved domains and are important for the survival of the cell under osmotic stress by controlling water or glycerol transport. Genetic defects in the aquaporin genes are involved in diseases such as diabetes insipidus, obesity and cataracts among others. Human aquaporin 10 (hAQP10) is one of the most recent identified members of the human aquaporin family of proteins of which there are 13 proteins in total. hAQP10 is defined as an aquaglyceroporin found in the small intestine where it may be involved in the absorption of water and small nutrients. Recent studies indicate that hAQP10 is also expressed in the skin, where it might be involved in the hydration and elasticity of the skin and hence has a role in eczema. As compared to many other aquaporins, hAQP10 is relatively uncharacterized and there is no known three-dimensional structure of this interesting target, neither of any other human aquaglyceroporin, in the databases. Specific aims are to determine the X-ray structure of hAQP10 using a novel approach for stabilization of aquaglyceroporins applying random mutagenesis. The ultimate goal is to find mutants resulting in functional protein with increased stability in detergents amendable for membrane protein crystallization.