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 (PubMed:21788334, PubMed:30026317). 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) (PubMed:21788334, PubMed:21855801). Required for cytoplasmic polyadenylation of mRNAs involved in carbohydrate metabolism, including the glucose transporter SLC2A1/GLUT1 (PubMed:28383716). 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 (PubMed:18172165). Mediates 3' adenylation of the microRNA MIR21 followed by its 3'-to-5' trimming by the exoribonuclease PARN leading to degradation (PubMed:25049417). Mediates 3' adenylation of H/ACA box snoRNAs (small nucleolar RNAs) followed by its 3'-to-5' trimming by the exoribonuclease PARN which enhances snoRNA stability and maturation (PubMed:22442037). 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 (PubMed:21855801). Interacts with CPEB1; the interaction is required for TENT4B-mediated translational control (PubMed:28383716). Predominantly expressed in the cytoplasm (PubMed:18172165). Belongs to the DNA polymerase type-B-like family. Was originally thought to have DNA polymerase activity. Extended N-terminus. Truncated N-terminus.