Figure 4. Split PE3 inhibits protein synthesis following structural complementation in a dose-dependent manner.

Rabbit reticulocyte lysate (RRL) was treated with various purified constructs as indicated for 30 min. prior to the addition of 400 ng of luciferase mRNA. Residual translational activity was measured as [³⁵S]-labeled luciferase or by luciferin chemiluminescence. A, Lysate were treated with the indicated protein constructs at 300 nM in the presence or absence of 50 µM NAD⁺. Densitometric measurements of [³⁵S] incorporation for all samples, except for intact PE3 and the α+β heterodimer in the presence of NAD⁺, were randomly ±15%. B, RRL was titrated with intact PE3 (solid squares) or TEV-activated PE3 α+β heterodimer (open squares) in the presence of 50 µM NAD⁺. C, Titration with NAD⁺ in the presence of 300 nM intact PE3 (solid) or α+β heterodimer (open). Symbols represent means of four experiments ± SEM. Lines are best fits to the Hill equation.