Strategies towards targeting Gαi/s proteins: Scanning of protein-protein interaction sites to overcome inaccessibility.

Heterotrimeric G proteins are classified into four subfamilies and play a key role in signal transduction. They transmit extracellular signals to intracellular effectors subsequent to the activation of G protein-coupled receptors (GPCRs), which are targeted by over 30% of the FDA-approved drugs. However, addressing G proteins as drug targets represents a compelling alternative, e.g. when G proteins act independently of the corresponding GPCRs, or in cases of complex multifunctional diseases, when a large number of different GPCRs is involved. In contrast to Gαq, efforts to target Gαi/s by suitable chemical compounds was not successful so far. Here, a comprehensive analysis was conducted examining the most important interface regions of Gαi/s with its upstream and downstream interaction partners. By assigning the existing compounds and the performed approaches to the respective interfaces, the druggability of the individual interfaces was rank ordered to provide perspectives for selective targeting of Gαi/s in the future.