text_1: Pre-mRNAs associated with spliceosomal components are less stable than unassociated splicing substrates.
text_2: Importantly, modifications in reaction conditions can lead to the accumulation, isolation, and characterization of reaction intermediates, a prerequisite for gaining mechanistic insights into how the spliceosome carries out intron removal, and how regulatory elements assist the general splicing machinery in defining splice sites and alternative exons.