Aquaporin, aka the "plumbing system for cells", is a transport protein that mediates the passage of water molecules in and out of a cell. It is a tetramer (has four identical units) with each subunit creating a channel. This protein is very important for our kidney which processing a large amount of water on a daily basis. Peter Agre who discovered this protein was awarded the Nobel Prize in Chemistry in 2003.The STL File of this protein was created using PyMOL, First, you download the PDB file from the protein databank website (http://www.pdb.org) for protein molecule 1FQY. Open PyMOL program, then go to File, Open and load the PDB file you just downloaded. Select to display the surface profile, on the right control panel of your viewer, click on S and select show as: surface. This will take a few seconds to load the surface profile. Now you can save this image as VRML 2 WRL file. The VRML file can be then be viewed and converted into STL file using a 3D modeling software such as Blender.