Pertussis toxin protein subunit S1 (S1)

Pertussis toxin protein subunit S1 is the catalytically active "A" component of the AB5-type exotoxin produced by Bordetella pertussis, which causes whooping cough. The holotoxin consists of six polypeptides arranged in an A-B structure; S1 forms the A protomer responsible for enzymatic activity while other subunits form a pentameric B oligomer that mediates cell binding. The primary function of S1 is ADP-ribosylation—specifically modifying α-subunits of heterotrimeric Gi/o proteins—thereby disrupting intracellular signal transduction by preventing these G proteins from interacting with their receptors. This leads to increased cAMP levels within host cells and contributes significantly to disease pathology. The unique mechanism has also made it valuable as a biochemical tool for studying G-protein-coupled receptor signaling pathways and as an antigen in acellular vaccines against Bordetella pertussis infection[2][3].

Other names

Pertussis toxin S1 subunitPTX-S1ptxS1

For drugs or antibodies targeting this molecule (e.g., vaccine-induced antibodies): Neutralization of enzymatic activity by binding to the S1 domain. For pertussis toxin itself as a tool compound: Catalyzes ADP-ribosylation of Gi/o alpha-subunits, locking them in an inactive GDP-bound state and preventing normal G protein-coupled receptor signaling[2][3].