Alzheimer disease (AD) is characterised by the accumulation of beta amyloid peptide cut from a transmembrane precursor. A large intramembrane complex carries out the proteolysis: gamma-secretase, containing the protease presenilin and other three proteins (nicastrin, aph1, pen2). G-secretase is involved also in the proteolysis mediated signaling cascade by the transmembrane receptors Notch1 and Erb4, regulating cell growth and differentiation The aim of the project is to gain structural insight into the architecture of the g-secretase and its mutant variants involved in AD by cryo-Electron Microscopy (EM) and into substrate binding by 2D electron crystallography; 3D X-ray crystal structure of presenilin will be fit in EM map Getting structural information of g-secretase is important at cellular level (involvement in signal transduction pathways), structural (few membrane protein structures described), biochemical (intramembrane proteolysis) and biomedical (involvement in a widespread neurodegenerative disease) The project will be developed in USA in EM lab of Prof Ubarretxena Belandia (NYSBC and Mount Sinai SM) in collaboration with Prof Sisodia (Dept Neurobiology Univ of Chicago) providing purified g-secretase and performing functional studies. Return host is the Univ of Rome La Sapienza (Dept Biochem Sciences, Biocrystallography Unit, Prof Vallone) Structural and structural-dynamic studies are progressively focusing on larger macromolecular complexes: for these crystallography is demanding in purification and crystallization, meanwhile cryoEM is becoming the election technique The fellow will bring back to Rome know-how in cryoEM and 2D crystallography to study structures and dynamics of large assemblies to be integrated with 3D X-ray crystallography of single subunits. He will develop as independent researcher contributing to the progress of group in Rome and to build a solid intercontinental collaboration with a state of the art institution