FIG. 1.

Inhibition of protein synthesis by wild-type or mutant Stx1As. Rabbit reticulocyte lysates were preincubated with periplasmic extracts containing wild-type Stx1A (○) or F226Y (▵), A231D (▿), G234E (◊), or A231D-G234E (□) mutant Stx1A at the dilutions indicated. Background activity (omitted mRNA) was subtracted from each value, and percent protein synthesis was determined by comparison to the control reaction preincubated with buffer only. Datum points are the means in one representative experiment ± the SE.