FIG. 8.

(A) Imp3p and Imp4p are protein components of the U3 snoRNP. Immunoprecipitations were performed with lysates from the epitope-tagged strains and the indicated antibodies. The RNA from bound RNPs was extracted and analyzed by denaturing gel electrophoresis followed by Northern blotting. Probes were used to detect the U3 and U14 box C/D snoRNAs and snR10, a box H/ACA snoRNA. Lanes 1 to 4 represent total RNA extracted from the same amount of lysate used for immunoprecipitation. (B) Imp3p and Imp4p are specific protein components of the U3 snoRNP. Immunoprecipitations were performed with the indicated antibodies and lysates from the indicated strains. RNAs from the resulting bound RNPs was isolated and analyzed by labelling with [5′-³²P]cytidine 3′,5′-bis phosphate and T4 RNA ligase, followed by denaturing gel electrophoresis.