This domain is found at the C-terminal end of Putative poly(A) polymerase catalytic subunit from Acanthamoeba polyphaga mimivirus (APMV). This entry comprises domains D3 and D4. D3 is very similar to the D2 domain (part of Pfam:PF19244) and shows the typical topology of a nucleotidyltransferase (NT) domain made of a mixed five-stranded beta-sheet and two connecting helices. D4 is an extension that the entrance of the central tunnel at the interface of the dimer [1].

1: mRNA maturation in giant viruses: variation on a theme. Priet S, Lartigue A, Debart F, Claverie JM, Abergel C; Nucleic Acids Res. 2015;43:3776-3788. PMID:25779049