Synonyms:65K, CGI 21, HSPC332, PRO2855, SAD1, SAD1 homolog, SNRNP65, USP39 Background:Plays a role in pre-mRNA splicing as a component of the U4/U6-U5 tri-snRNP, one of the building blocks of the spliceosome. Regulates AURKB mRNA levels, and thereby plays a role in cytokinesis and in the spindle checkpoint. Does not have ubiquitin-specific peptidase activity, but could be a competitor of ubiquitin C-terminal hydrolases(UCHs).