Figure 3.

Requirements for recognition of the 5′ repeat-derived crRNA tag sequence. In all panels, the indicated recombinant Cmr proteins were incubated with an 8-nt tag RNA (modified where indicated and generally 3′ end-labeled unless noted). RNA and complexes were resolved by native gel electrophoresis. Diagrams indicate the positions of unbound crRNA and crRNPs (in the absence and presence of proteins, respectively). (A) Individual Cmr proteins required for 5′ tag RNA binding by the full complex. (B) Individual Cmr proteins required for 5′ tag RNA binding by the Cmr2–5 subcomplex. (C) Sequence required for 5′ tag RNA binding by the Cmr2–5 subcomplex. Wild-type (AUUGAAAG) and mutated (UAACUUUC) tag RNAs were analyzed as indicated. (D) End groups required for 5′ tag RNA binding by the Cmr2–5 subcomplex. See the Materials and Methods for details about preparation of RNAs with the indicated 5′ and 3′ chemical end groups.