Binding of small molecules to their targets triggers complex pathways. Computational approaches are keys for predictions of the molecular events involved in such cascades. Ultimately, therefore, understanding of these events, requires the integration of detailed molecular information into the study of biological complexes. In other words, computational systems biology needs to be paralleled by a quantitative description at the molecular level. In this talk I will review current efforts at computationally characterizing the molecular determinants in the largest membrane-bound receptor family, the G-protein-coupled receptors (GPCRs). I will focus on odorant receptors, which constitute more than half GPCRs. The work presented in this seminar uncovers structural and energetic aspects of components of the cellular cascade.