Figure 3.

Activity assays for EcPltAB. a, ADP-ribosyltransferase assays similar to those used in Fig. 2 using biotinylated NAD⁺ as a substrate to modify recombinant HsGαi3ΔN PT (left) and EcPltAB (right) holotoxins were monitored for activity for 5 min at 37 °C in the presence of 10 mm (+) or 100 mm (++) TCEP and with or without 10 mm ATP. b, EcPltAB activation in the presence of different ratios of reduced (GSH) or oxidized (GSSG) glutathione within the ADP-ribosylation assay. c, 2D isoelectric focusing separation of different Ga_i isoforms isolated from bovine brain extract following treatment with EcPltAB or PT indicate multiple Ga_i isoforms act as substrates.