Cytoplasmic non-canonical poly(A) RNA polymerase that catalyzes the transfer of one adenosine molecule from an ATP to an mRNA poly(A) tail bearing a 3'-OH terminal group and participates in the cytoplasmic polyadenylation (PubMed:33882302). Polyadenylates mRNA encoding extracellular matrix constituents and other genes crucial for bone mineralization and during osteoblast mineralization, mainly focuses on ER-targeted mRNAs (By similarity). ATP + RNA(n) = diphosphate + RNA(n)-3'-adenine ribonucleotide Widely expressed, with preferential expression observed in the retina compared to other ocular tissues (PubMed:12054608). Also expressed in osteoblasts (PubMed:29358272). The disease is caused by variants affecting the gene represented in this entry. Belongs to the TENT family. Truncated N-terminus.