DIS3, belonging to the ribonuclease II (RNB) family, has a 3'-5' exonuclease activity. It is a catalytic component of the exosome 3'->5' exoribonuclease complex required for the 3'-processing of the 7S pre-RNA to the mature 5.8S rRNA and for mRNA decay. The protein is implicated in mitotic control and essential for cell division and spore germination. It may be involved in regulating protein dephosphorylation during mitosis.