Figure 5.

U100 is a novel member of the scaRNA family. (A) Subfractionation of HeLa cells. RNA isolated either from total HeLa cells (Tot) or from cytoplasmic (Cyt), nuclei (Nu), nucleoplasmic (Np) or nucleolar (No) fractions was analysed in a 6% acrylamide/7 M urea gel and the various snoRNAs detected by northern blot analysis using specific oligonucleotide probes. Hybridisations with U3- and U6-specific probes have been used as controls of the cell fractionation procedure. (B) In situ hybridisation showing the localisation of transfected human U100. HeLa cells co-transfected with pCMV-hU100 and pGFP-coilin were hybridised with a specific U100 fluorescent oligonucleotide. The Cajal bodies are visualised by co-expressing GFP–coilin fluorescent protein. The merged picture shows that U100 co-localises with coilin. (C) Schematic representation of the terminal loops of the 5′ and 3′ hairpins of U100. The predicted Cajal body-specific localisation signals (27) are indicated in bold.