FIGURE 5.

Lsm1–7 loads single stranded RNA from the 3′ end. (A) Cut-away view of the pore of Lsm1–7 bound to AUUUUG. Lsm3 and Lsm6 are omitted for clarity. (B) Synthetic RNAs used for binding tests, in which the 3′ or 5′ end is blocked from binding (or threading through) the pore of the Lsm1–7 ring by the presence of the hairpin structure. (C) Wild-type Lsm1–7 tightly binds the 5′ hairpin RNA and has weak binding for RNAs harboring a 3′ hairpin. Deletion of the carboxy-terminal region of Lsm1 does not significantly alter the binding specificity with respect to 3′ or 5′ hairpins.