Fig. 3.

Major and minor snRNPs are found predominantly in the nucleus of HeLa cells. (A, C) RNA was recovered from HeLa nuclear (n) or cytoplasmic (c) extract (in both cases corresponding to 3 × 10⁶ cell equivalents) or from purified snRNPs (s) and fractionated by denaturing PAGE. Northern blot analysis was performed with a mixture of ³²P-labeled probes against U1, U2, U4, U5, and U6, followed by 5S RNA and tRNA (A), or against U11, U12, or U4atac and U6atac (C). (B, D) The amount of a given RNA in nuclear and cytoplasmic extract was quantitated by PhosphorImager analysis and the percent of the total (nucleus plus cytoplasm) is shown graphically. (E) Proteins were recovered from 3 × 10⁶ cell equivalents of nuclear (n) or cytoplasmic extract (c) and separated by SDS/PAGE. Immunoblotting was performed with the indicated antibodies.