Terminal nucleotidyltransferase 5B (TENT5B)

Terminal nucleotidyltransferase 5B (TENT5B) is a human enzyme encoded by the *TENT5B* gene, previously known as *FAM46B*. It functions as a non-canonical poly(A) polymerase, catalyzing the addition of adenosine to mRNA poly(A) tails, and thus regulates mRNA stability and translation. TENT5B contains a larger N-terminal catalytic domain compared to other eukaryotic poly(A) polymerases and is structurally similar to prokaryotic PAP/CCA-adding enzymes. It is localized to both cytoplasm and nucleus and is highly expressed in human pre-implantation embryos and pluripotent stem cells, but is sharply down-regulated following differentiation. TENT5B is essential for the maintenance of protein synthesis and viability in embryonic stem cells, with knockout causing apoptosis and lethality. Recent studies highlight its critical role in gametogenesis (oogenesis), where its loss leads to infertility, particularly in mouse models[1][2][3][5][8][11].

Other names

TENT5BFAM46BFamily with sequence similarity 46 member BNon-canonical poly(A) polymerase FAM46BMGC16491Putative nucleotidyltransferase FAM46BProtein FAM46B