Fig. 2. Characterization of the novel RNAs. (A) Immunoprecipitation of human snoRNPs. An extract prepared from HeLa cells was incubated with protein A–Sepharose saturated with anti-fibrillarin (α-Fib) or anti-GAR1 (α-Gar) antibodies. Upon collection of Sepharose beads by centrifugation, RNAs were recovered by proteinase K treatment and phenol extraction. Distribution of RNAs was determined by RNase A/T1 mapping using sequence-specific antisense RNA probes as indicated on the right. Control mappings performed with E.coli tRNA (C) or RNAs obtained from the HeLa cell extract (E) are also shown. Mock represents control reaction with protein A–Sepharose alone. Lane M, size markers (terminally labelled HaeIII- and TaqI-digested pBR322). (B) Intracellular localization. RNA isolated either from HeLa cells (T), or from nuclear (Nu), nucleoplasmic (Np), nucleolar (No) or cytoplasmic (Cy) fractions of HeLa cells were analysed by RNase A/T1 mapping using sequence-specific RNA probes. Lane C represents control mapping with E.coli tRNA.