Component of the cleavage factor Im (CFIm) complex that plays a key role in pre-mRNA 3'-processing. Involved in association with CPSF6 or CPSF7 in pre-MRNA 3'-end poly(A) site cleavage and poly(A) addition. NUDT21/CPSF5 binds to cleavage and polyadenylation RNA substrates. The homodimer mediates simultaneous sequence-specific recognition of two 5'-UGUA-3' elements within the pre-mRNA. Binds to, but does not hydrolyze mono- and di-adenosine nucleotides. May have a role in mRNA export.
Belongs to the Nudix hydrolase family. CPSF5 subfamily. Contains 1 nudix hydrolase domain.
Acetylated mainly by p300/CBP, recruited to the complex by CPSF6. Acetylation decreases interaction with PAPAO. Deacetylated by the class I/II HDACs, HDAC1, HDAC3 and HDAC10, and by the class III HDACs, SIRT1 AND SIRT2.
Nucleus. In punctate subnuclear structures localized adjacent to nuclear speckles, called paraspeckles.