SRP RNA mutant lacking helix 6 (ΔH6 in Fig. 4). Shown are fluorescence patterns at 30 sec (A), 3 min (C), 12 min (D), 26 min (E), and 43 min (F) after nuclear microinjection. (B) Phase-contrast at 1 min. Note the early, transient nucleolar localization, similar to that observed for full-length SRP RNA (Fig. 2) and the Alu domain mutant (Fig. 5).