FIGURE 6.

Ribosome-dependent GTPase stimulation of eEF2 by the chimeric IGR IRES. GTP hydrolysis was monitored by incubation of 80S, eEF2, and the indicated IRES with radiolabeled [γ-³²P]GTP. Aliquots of the reaction were quenched over time and then resolved by thin-layer chromatography. The slope of the linear regression lines, which represents the mean percent hydrolysis of radiolabeled GTP per minute, is shown in a bar graph. These values were derived from three independent experiments, and the error bars correspond to a 95% confidence interval. Note that ribosomes alone (-IRES/-eEF2) do not stimulate GTPase activity.