FIGURE 2.
Specific activity of WT and mutant AID proteins expressed in Sf9 insect cells or in E. coli. Deamination-specific activities were measured using 36 nt of 32P-labeled ssDNA containing a single C target in an AGC hot spot motif. Reactions were carried out for 5 min at 37 °C in the presence of ssDNA (500 fmol) and recombinant GST-AID (200 fmol) expressed in Sf9 cells or with of GST-AID (6400 fmol) expressed in E. coli. Due to its extremely low specific activity, the E. coli-expressed AID was present at ∼32-fold higher concentration than Sf9-expressed AID. The error bars represent ±1 S.E. from at least three independent measurements.