Cleavage And Polyadenylation Specific Factor 3 Like Protein (CPSF3L)

The Integrator complex contains at least 12 subunits and associates with the C-terminal domain of RNA polymerase II large subunit (POLR2A) and mediates the 3-prime end processing of small nuclear RNAs U1 (RNU1) and U2 (RNU2). INTS11, or CPSF3L, is the catalytic subunit of the Integrator complex.

By searching for members of the beta-lactamase superfamily, Dominski et al. (2005) identified CPSF3L, which they called RC68. The deduced 600-amino acid protein contains an N-terminal histidine motif involved in zinc binding and catalysis, suggesting that RC68 functions as an RNA-specific endonuclease. Fluorescence- and epitope-tagged RC68 was expressed in both the nucleus and cytoplasm of transfected HeLa cells, with higher concentrations in the nucleus.