URT1 and HESO1 can tail AGO1-bound miRNAs.

<p>Nucleotidyl transferase assays were conducted with recombinant URT1, HESO1, or no enzyme as indicated, AGO1 immunoprecipitate (IP) as the substrate, and cold UTP. AGO1 IP was prepared from <i>hen1-2 heso1-2 urt1-3</i> so that the associated miRNAs lack 2’-<i>O</i>-methylation or tailing. After the reactions, the reaction mixes were separated into the precipitate (P) and supernatant (S) fractions and the RNAs were isolated separately from the two fractions and subjected to northern blotting to detect miR165/6 and miR172. The lanes “ctrl” were total RNA from wild type included during gel electrophoresis. The smaller brackets indicate full-length miRNAs from wild type. Both full-length and 3’ truncated miRNAs were present in the AGO1 IP from <i>hen1-2 heso1-2 urt1-3</i>. The larger brackets indicate tailed miRNAs.