Responsible for the post-transcriptional adenylation of the 3'-terminal of mRNA precursors and several small RNAs including signal recognition particle (SRP) RNA, nuclear 7SK RNA, U2 small nuclear RNA, and ribosomal 5S RNA. {ECO:0000269|PubMed:11287430, ECO:0000269|PubMed:11463842}. This is the function of PAPOLG (poly(A) polymerase gamma, ENSG00000115421).