Spliceosomes are large ribonucleoproteins that remove introns from nuclear pre-mRNA in a two-step reaction. CCDC49 is a 425 amino acid protein that is involved in the catalytic steps of splicing in Saccharomyces cerevisiae. CCDC49 associates with a component of the Prp19-associated complex, CEF1, which is involved in spliceosome activation. It is likely that CCDC49 facilitates juxtaposition of the 5’ splice site and branch point during the final step in the first catalytic reaction. There are two isoforms of CCDC49 that are produced as a result of alternative splicing events.