FIG. 6.
TbMP18 is not necessary for the 3′-U-exo activity but augments TUTase activity at an editing site. Assessments of specific 3′-U-exo activity (A), specific TUTase activity (B), and basic TUTase activity (C), using substrates diagramed below, are shown. (In panel C, 1x equals 0.24 μg protein.) In this and all subsequent experiments with precleaved substrates, the position of the labeled input oligo (in), partial (−1U and −2U) and complete (−3U) removal products, and complete addition product (+2U) are indicated. For basic TUTase activity, the input (in) and major product (+1U), as well as longer addition products (Un, likely produced by the p108 TUTase, shown in a darker exposure) are indicated.