The function of ENSG00000158246 (TENT5B, terminal nucleotidyltransferase 5B) is as follows. Catalyzes the transfer of one adenosine molecule from an ATP to an mRNA poly(A) tail bearing a 3'-OH terminal group in an ATP hydrolysis-dependent manner (PubMed:32009146, PubMed:34048638). May be involved in maintaining the translation efficiency of at least some genes through preventing degradation of their mRNAs (PubMed:32009146). Prefers RNA molecules that are adenosine-rich close to 3'-end (PubMed:32009146). In addition, may inhibit cell proliferation and cell cycle progression through ubiquitination of beta-catenin/CTNNB1 (PubMed:30532005). {ECO:0000269|PubMed:30532005, ECO:0000269|PubMed:32009146, ECO:0000269|PubMed:34048638}.