Linking Splicing to Pol II Transcription Stabilizes Pre-mRNAs and Influences Splicing Patterns
(A) Diagrams of the wt β-globin minigene DNA template with the Pol II promoter (top), the T7 promoter (middle), or the pre-synthesized RNA transcript (lower). (B) Representative autoradiograms show the time course of the transcription/splicing UTP chase experiment for Pol II- (left) or T7- (middle) generated transcripts, and the splicing profile of pre-synthesized pre-mRNAs (right). For the transcription/splicing UTP chase experiment, the zero time point refers to the initiation of the chase reaction through the addition of excess unlabeled UTP. Pre-mRNA transcript, spliced product, and intermediate lariat bands are indicated. The pre-synthesized pre-mRNA (right) is capped. (C) Quantitation of the data in (B) by computing the fraction spliced ([lariat] + [product])/ ([lariat] + [product] + [pre-mRNA]). (D) Quantitation of transcript degradation ([lariat] + [product] + [pre-mRNA]).