This gene encodes one of three subunits which combine to form cleavage stimulation factor (CSTF). CSTF is involved in the polyadenylation and 3'end cleavage of pre-mRNAs. Similar to mammalian G protein beta subunits, this protein contains transducin-like repeats. Several transcript variants with different 5' UTR, but encoding the same protein, have been found for this gene.