Plays a role in pre-mRNA splicing as a component of the U4/U6-U5 tri-snRNP, one of the building blocks of the precatalytic spliceosome. Regulates AURKB mRNA levels, and thereby plays a role in cytokinesis and in the spindle checkpoint. Does not have ubiquitin-specific peptidase activity.,USP39, 65K, CGI-21, HSPC332, SAD1, SNRNP65, ubiquitin specific peptidase 39,Epigenetics & Nuclear Signaling,Cell Biology & Developmental Biology,Ubiquitin,USP39