**4. Conclusion**

Membrane proteins, as we saw, are of fundamental importance for the survival of any living being. A deep insight into the molecular mechanisms underlying their function is thus needed for a complete characterization of the way our cells communicate with the rest of the world. Obviously, a complete characterization implies the passage through the structural features of the membrane proteins. Unfortunately, as of today, the structural biology scientific community still finds several inconvenients to systematically solve the structure of membrane proteins, albeit giant steps forward were carried out in the last few years. Moreover, we have to consider that the main challenges for the near future will include the development and application of methods that permit the full description at the molecular/structural level of large protein complexes, most of all including membrane proteins with unknown structure.

In this chapter we have described two examples for which an experimental/computational multidisciplinary approach was shown to be the key for the gaining of insights into complex systems. In both cases not only 'static' structural elements have been identified, but also putative dynamical mechanisms, comprising large conformational changes. Indeed, we have demonstrated that advancements in experimental structural biology, extensively combined with state-of-art computational biology tools and model-guided molecular biology experiments may become extremely effective for the characterization of complex molecular mechanisms including membrane proteins. These observations make us confident that more difficult challenges of structural/functional characterization can be undertaken in short time and that these approaches may provide a great improvement to our understanding of cell and molecular biology events.
