Human LUC7 proteins impact 5’ splice sites with distinct composition. Credit: Connor J. Kenny et al RNA splicing is a cellular process that is critical for gene expression. After genes are copied from DNA into messenger RNA, portions of the RNA that don't code for proteins, called introns, are cut out and the coding portions are spliced back together. This process is controlled by a large protein-RNA complex called the spliceosome. MIT biologists have now discovered a new layer of regulation tha...