Yeast U6 snRNA made by RNA polymerase II is less stable but functional

Evidence for methylguanosine-capping of U6 snRNA made by RNAP II. Total RNA from an SNR6 disruption strain with pRS314-SNR6 (WT) or pRS314-GAL-SNR6-II (GAL-SNR6-II) was heated for 1 min at 90°C, then hybridized to ³²P-labeled oligonucleotide probes specific for U4 or U6 snRNA. The RNA was then incubated with the indicated amount of mAb H20, which binds TMG or MMG caps, prior to electrophoresis on a nondenaturing gel. The positions of free U4 and U6 snRNAs, and mAb-shifted snRNAs are indicated. A minor band consistent with base-paired U4/U6 is also seen in both samples.