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. 2003 Nov 15;31(22):6543–6551. doi: 10.1093/nar/gkg849

Figure 3.

Figure 3

The U99 snoRNA gene is transcribed in the opposite orientation to its host intron. (A) Schematic representation of a part of the mouse (top) and human (bottom) genes hosting U99 snoRNA. Exons 3 and 4 are represented by white boxes, while splicing events are denoted by dotted lines. The U99 snoRNA gene is schematised by a white arrow indicating transcription orientation. Thin black arrows denote the transcription orientation of the indicated genes. Several spliced ESTs (i.e. BU588934, BF219096, BU588653 and BI461867 in human, and a single one, AK011444, in the mouse) overlapping and in the same orientation as the U99 snoRNA gene are also depicted (filled boxes denote exons). Not drawn to scale. (B) U99 does not immunoprecipitate with R1131 antibody. Total RNA from HeLa cells was subjected to immunoprecipitation with R1131 antibody (specific for the trimethyl cap structure), and RNAs recovered from either the pellet or supernatant were assayed for U99 by northern blot hybridisation with a U99-specific oligonucleotide probe. 1, input RNA (1:10); 2, pellet; 3, supernatant (1:10). The 5′-trimethyl-capped snoRNA U3 and the intron-encoded U98 and U102 snoRNAs were used as positive and negative controls, respectively.