Fig. 1. Preparation of SNAPc-containing Pol II PIC on non-coding RNA promoters.
a, SDS–PAGE analysis of SNAPc variants (FL and core) purified to homogeneity. The experiments were repeated at least three times. b, EMSA showing the binding of SNAPc (with or without TBP and TFIIB) to U1 and U5 promoter DNA. The presence of SNAPc stabilizes the binding of TBP–TFIIB to snRNA promoters. The experiment was repeated at least three times. c, SDS–PAGE analysis of SNAPc-containing Pol II PIC variants isolated through sucrose gradient ultracentrifugation. The experiments were repeated at least three times. d, In vitro transcription assay showing the relative influence of SNAPc variants on Pol II snRNA transcription with different combinations of GTFs. The gel is representative of triplicate experiments. e, Histogram plots representing the quantification (Methods) of full-length transcripts from the in vitro transcription assay in d. The presence of TFIIH with or without SNAPc leads to roughly four to seven fold increases in the formation of background RNA products. Data are presented as mean ± s.d. The error bars have been derived from three independent experiments.