 RNA catalyses nuclear pre-mRNA splicing by Sebastian M. Fica and others

Nature 503, 229–234 (2013), DOI 10.1038/nature12734. Author-hosted original PDF: full first-author byline Sebastian M. Fica, page 229; co-first-author contribution marked. Abstract and Figures 1–3: sulfur substitution/metal rescue in assembled yeast spliceosomes identifies U6 ligands positioning catalytic metals during both splicing reactions. No claim of protein-free splicing by the intact cellular machinery.