The structure of the Ca2+-ATPase of sarcoplasmic reticulum will be analyzed by crystallographic and spectroscopic techniques. One aim of the work will be to produce three-dimensional crystals of the Ca2+ transport ATPase in appropriate size and stability for high resolution X-ray diffraction analysis. In addition, reconstruction of the structure of Ca2+-ATPase by electron microscopy of the E1 and E2type two-dimensional Ca2+-ATPase crystals will be refined and the structural differences between the E1 and the E2 conformations identified. The information obtained will be correlated with kinetic data to develop a molecular description of the Ca transport process. The complete molecular machinery required for the ATP-dependent translocation of Ca2+ from the cytoplasm into the lumen of sarcoplasmic reticulum is contained in the Ca2+ transport ATPase. The Ca2+-ATPase is present in different iso-forms in the sarcoplasmic reticulum of slow or fast skeletal, cardiac and smooth muscles. These data will fill an important gap in our knowledge of the structure of sarcoplasmic reticulum and will significantly contribute to the elucidation of the molecular mechanism of calcium transport.
