Employing biophysical, biochemical and reverse genetic approaches, we will analyse two processes essential for assembly and budding of Influenza virus: Recruitment of the envelope protein M2 and the coat protein M1 to the viral budding site and the generation of membrane curvature induced by oligomerization of M1 and membrane insertion of an amphiphilic helix of M2. Viruses must be assembled in such a way that this assembly can be reversed later on in subsequent infections in a coordinated, serial manner. The results will provide a molecular understanding how the functions each protein has for both processes are regulated.