Table 1. Effect of tRNA on EB inhibition of substrate cleavage.

	–tRNA	+tRNA (38 µM)
No EB	[100%]	66%
20 µM EB	19%	68%

Substrate cleavage assays were carried out as described in Materials and Methods and used 5′-³²P-labeled R1.1[WC] RNA. Reactions were quantitated by phosphorimaging. The reported values are the averages of two experiments. The amount of substrate cleavage obtained in the absence of tRNA and EB (4.1 ± 2.7%) was normalized to 100% (indicated by the brackets). A nominal amount of tRNA (estimated to be ∼0.02 µM) is already present in the cleavage reactions, which derived from the substrate purification procedure. Note that there is a slight inhibition of cleavage (34% reduction) conferred by 38 µM tRNA in the absence of EB.