Step-by-step explanation:
The pathway that includes three G-proteins (α,β,γ) is the GPCR pathway. The GPCR stands for G-protein coupled receptor pathway that includes serpentine multipass trans-membrane receptor. The N-terminal of the receptor is towards the extracellular side and C-terminal is located inside the cytoplasmic side.
The ligand gets attached with the receptor that allows the conformation change in the receptor and allows it to interact with the G protein. The Gα-subunit replaces GDP with GTP and removes from Gβ and Gγ subunits. Thus, activating the effector molecules like guanyl cyclase and adenyl cyclase.
The pertussis toxin is a strong inhibitor of chemotaxis as it allows ADP-ribosylation of Gi α-subunit and keeps α-subunit with GDP bound. Thus, preventing it from regulating the target protein. This leads to whooping cough.