FIGURE 3.
Comparison of the U4atac pentaloop and a UUCG tetraloop. Stereo ribbon plot of the U4atac pentaloop and His270 of hPrp31 (top) compared with the organization of a UUCG RNA tetraloop (bottom; PDB ID: 1F7Y). Coloring as before; tetraloop RNA, beige. G41 and U44 of the U4atac RNA, His270 of hPrp31, and the equivalent elements of the tetraloop are shown as sticks, colored by atom type and labeled. The C3 nucleotide of the tetraloop, which takes the equivalent position of His270, is also colored steel blue. Dashed lines indicate hydrogen bonds. Rotated 120° about the vertical axis compared with Figure 1B.
