Subunit of CPF cleavage and polyadenylation factor and E3 Ub-ligase; involved in 3' end formation of mRNA via cleavage and polyadenylation of pre-mRNA; binds pre-mRNA via the zinc knuckle and RING finger; E3 ubiquitin ligase involved in polyubiquitination of the endonuclease Ysh1p; contains a ubiquitin-like (UBL) domain, a RNA-binding zinc knuckle motif and a RING finger domain; possible role in ubiquitination of Pap1p; relocalizes to the cytosol in response to hypoxia; homolog of human RBBP6