The Calcium Pump

Calcium ATPase (the calcium pump) is a transport protein that facilitates the movement of calcium ions across the cell membrane. It ensures low concentration of Ca ions (needed for cell signaling) inside the cell by driving them out of the cell across an electrochemical gradient. The calcium ATPase plays an important role in muscle contraction. Two STL files are provided here showing the calcium pump in different configurations: the first one is an open position with no Ca ions (PDB ID: 1IWO) versus the closed position (PDB ID: 1SU4).