– S1 is an NAD-dependent ADP-ribosyltransferase, which plays a crucial role in the pathogenesis of B.pertussis causing disruption of normal host cellular regulation. It catalyzes the ADP-ribosylation of a cysteine in the alpha subunit of host heterotrimeric G proteins. In the absence of G proteins it also catalyzes the cleavage of NAD(+) into ADP-ribose and nicotinamide. It irreversibly uncouples the G-alpha GTP-binding proteins from their membrane receptors. PTX S1 Protein, Bordetella pertussis, Recombinant (His) is expressed in yeast with N-6xHis tag. The predicted molecular weight is 28.2 kDa and the accession number is P04977.