FIG. 1.

Complementing activity interacts with apo-B RNA in vitro. Partially purified complementing activity (10 mg) was incubated with the sense or antisense apo-B RNA affinity resins or with the beads alone as described in Materials and Methods. After an extensive washing, proteins were eluted with 0.5 M NaCl. The unbound fractions (unbound protein plus the first wash, 10 μg) and eluates (∼1 ng) were assayed for complementing activity in the presence of purified His₆-tagged apobec-1. The buffer control and the starting material (10 μg) are shown in the first panel. The positions of the primer extension products from the edited (UAA) and unedited (CAA) RNAs are marked on the right. The data were quantified by using NIH ImageQuant software, and the results are expressed as the percent editing, i.e., UAA/(UAA + CAA).