The IBS BAG includes in this proposal IBS teams and external groups from iRTSV/CEA (Grenoble), CEA-Cadarache (St Paul lez Durance) and IRBA (Brétigny-sur-Orge). We study structure-function relationships of proteins emphasizing in human health, biotechnology and methodology. Most of the projects are a continuation of the MX-2329 proposal and can be grouped in different topics as follows: host-pathogen interaction, new drug targets, fundamental cellular mechanisms, membrane proteins, intrinsically disordered proteins, biotechnological applications and methodology. Some of these projects use integrative approaches (X-ray crystallography, SAXS, NMR (and cryo-EM), together with other biophysical studies) with the aim to fully understand the complexity of the biological macromolecular systems on study. Some teams are dedicated to serial crystallography and its developments, for which the ESRF-EBS has become the perfect tool.