Component of the TRAMP (TRF4) complex which has a poly(A) RNA polymerase activity and is involved in a post-transcriptional quality control mechanism limiting inappropriate expression of genetic information. Polyadenylation is required for the degradative activity of the exosome on several of its nuclear RNA substrates like cryptic transcripts generated by RNA polymerase II and III, or hypomethylated pre-tRNAi-Met. Both complexes polyadenylate RNA processing and degradation intermediates of snRNAs, snoRNAs and mRNAs that accumulate in strains lacking a functional exosome. AIR2 also inhibits the methylation of NPL3 mediated by HMT1 through its interaction with HMT1. Component of the TRAMP complex (also called TRF4 complex) composed of at least HUL4, MTR4, PAP2/TRF4 and either AIR1 or AIR2. Interacts with HMT1 and NPL3. The interaction with NPL3 requires the presence of HMT1. Interacts directly with PAP2. Present with 1800 molecules/cell in log phase SD medium. Belongs to the AIR1 family.