Figure 5
From: Phosphorylation of HIV Tat by PKR increases interaction with TAR RNA and enhances transcription
PKR phosphorylation of HIV-1 Tat wild-type and mutants after 15 minutes and phosphorylation kinetics. (a) Proteins were phosphorylated by activated PKR at 30°C for 15 minutes in the presence of γ-32P-ATP. The reaction was stopped by the addition of protein loading buffer and incubation at 4°C. Samples were analyzed by 15% SDS-PAGE. Graph shows the results for three separate experiments. (b) Non-linear regression analysis of PKR phosphorylation curves of wild-type and mutant proteins was performed using a one-site binding hyperbola, which describes the binding of a ligand to a receptor and follows the law of mass action. K0.5 is the time required to reach half-maximal phosphorylation.