Fig. 5. In vitro assays of deaminase activity in wild-type and mutant worms. ³²P-labeled dsRNA was incubated with various amounts of protein extract, for 2 h at 20°C. In (A), reaction products were electrophoresed on a native gel, and a phosphorimage of the gel is shown. This assay is based on the fact that adenosine deamination changes the structure of a dsRNA and thus its mobility on a native gel. In (B), the conversion of [³²P]AMP to [³²P]IMP was measured directly by TLC. After incubation, RNA was isolated, digested to mononucleotides and chromatographed on a TLC plate; a phosphor image of the TLC plate is shown. Ori, origin; pI, [³²P]IMP; pA, [³²P]AMP.