Calmodulin (CaM) (an abbreviation for CALcium-MODULated proteIN) is a calcium-binding messenger protein expressed in all eukaryotic cells. CaM is a multifunctional intermediate messenger protein that transduces calcium signals by binding calcium ions and then modifying its interactions with various target proteins.: http://en.wikipedia.org/wiki/Calmodulin Model of mammalian Calmodulin based on the Protein Data Bank entry 3CLN: http://www.rcsb.org/pdb/explore/explore.do?structureId=3cln STL file created using VMD: http://www.ks.uiuc.edu/Research/vmd/ The protein backbone is represented in "cartoon" form. Calcium ions are present as spheres with calcium-binding residues and water molecules.Successfully printed by a Replicator 2 in PLA using MakerWare(TM) 2.4.1.24, standard resolution (3 shells, 25% infill), with raft and supports. Different representations are provided as a guide to coloring the molecule by hand. The calcium ions are shown in red.