Mapping of the altered RNA cleavage sites generated by L104R and E126D APE1 variants.

<p>(<b>A</b>) Recombinant WT APE1 (lane 4), variant L104R (lane 5), and variant E126D (lane 6), each at 1.4 µM, were incubated with 350 fmoles of 5′-³²P-radiolabeled c-<i>myc</i> CRD RNA for 25 min at 37°C in a total volume of 20 µl. Samples were run on a 12% polyacrylamide/7 M urea gel. For reference, an alkaline hydrolysis ladder was generated (lane 1) and RNase T1 digest of the c-<i>myc</i> CRD RNA (lane 3) was performed. Numbering on the left indicates guanosine residue sites cleaved by RNase T1 under denaturing conditions. Numbering on the right indicates sites cleaved by WT APE1 and the APE1 variants L104R and E126D. (<b>B</b>) Secondary structure of c-<i>myc</i> CRD RNA and the cleavage sites generated by WT APE1 (underlined) and APE1 variants L104R and E126D. The box at the bottom of the figure indicates the strong and weak cleavage sites generated by the endoribonucleases.