FIG. 3.

[³H]Tyr-labeled proteins and RNAs in a coupled tyrosylation-translation system. (A) Autoradiogram of a protein gel after sodium dodecyl sulfate-PAGE of coupled tyrosylation-translation reaction mixtures. The premix compositions of the various samples are indicated above the gel, molecular weight markers are shown on the left, and reference positions of BSA and TyrRS are shown on the right. For further details, see the text. (B and C) Tyrosylation kinetics were monitored for the TLS^BMV (B) and for yeast tRNA^Tyr (C). During the 60-min incubation of the [³H]tyrosylation mixture, samples were either directly quenched in TCA (○) or incubated in the presence of a 150-fold molar excess of RNase A for 2 min at 37°C prior to TCA precipitation, filtration, and liquid scintillation counting (•). All data are representative of three independent experiments.