FIGURE 2.

A6U and A6P3 cross-links with 5′ ³²P-labeled gA6-14-U5, (U5) (top panel) or gA6-14-U10 (U10) (bottom). U5 and U10 indicate that the position of the cross-linking agent (S⁴U or APA) was at the 5th or 10th uridylate, respectively, in the U-tail. B1 and B2 are two populations of cross-linked molecules. Asterisks represent intra-gRNA cross-links that were also present in the control lane (no mRNA) when the gel was overexposed (representative lane, labeled C) or were not consistently observed in all experiments. Due to limited amounts of sample, only 1/10 of the cross-linked molecules were used in the control lanes (no mRNA and no UV lanes).