Terminal nucleotidyltransferase that catalyzes preferentially the transfert of ATP and GTP on RNA 3' poly(A) tail creating a heterogeneous 3' poly(A) tail leading to mRNAs stabilization by protecting mRNAs from active deadenylation (By similarity). Also functions as a catalytic subunit of a TRAMP-like complex which has a poly(A) RNA polymerase activity and is involved in a post-transcriptional quality control mechanism. Polyadenylation with short oligo(A) tails is required for the degradative activity of the exosome on several of its nuclear RNA substrates. Doesn't need a cofactor for polyadenylation activity (in vitro). Plays a role in replication-dependent histone mRNA degradation, probably through terminal uridylation of mature histone mRNAs. May play a role in sister chromatid cohesion (By similarity). ATP + RNA(n) = diphosphate + RNA(n)-3'-adenine ribonucleotide Component of a nucleolar TRAMP-like complex, an ATP-dependent exosome regulatory complex consisting of a helicase (MTREX), an oligadenylate polymerase (TENT4B or TENT4A), and a substrate specific RNA-binding factor (ZCCHC7 or ZCCHC8). Several TRAMP-like complexes exist with specific compositions and are associated with nuclear, or nucleolar RNA exosomes. Predominantly expressed in the cytoplasm. Belongs to the DNA polymerase type-B-like family. Was originally thought to have DNA polymerase activity. Extended N-terminus.