Pertussis toxin is widely used in research to study G-protein-coupled receptor signaling pathways. It specifically inhibits the function of inhibitory G-proteins (Gi), leading to increased levels of cyclic AMP (cAMP) in cells. This makes it a valuable tool for investigating cellular processes regulated by cAMP, such as immune responses, hormone signaling, and neurotransmission. Additionally, it is utilized in vaccine development and testing, as it is a key component of the Bordetella pertussis bacterium, which causes whooping cough. Researchers also employ it to explore the mechanisms of bacterial pathogenesis and to develop therapeutic strategies targeting G-protein signaling.