Protein Domain : Poly(A) polymerase, RNA-binding domain IPR007010

Type	Domain
Description	In eukaryotes, polyadenylation of pre-mRNA plays an essential role in the initiation step of protein synthesis, as well as in the export and stability of mRNAs. Poly(A) polymerase, the enzyme at the heart of the polyadenylation machinery, is a template-independent RNA polymerase that specifically incorporates ATP at the 3' end of mRNA. The crystal structure of bovine poly(A) polymerase bound to an ATP analogue at 2.5 A resolution has been determined [ ]. The structure revealed expected and unexpected similarities to other proteins. As expected, the catalytic domain of poly(A) polymerase shares substantial structural homology with other nucleotidyl transferases such as DNA polymerase beta and kanamycin transferase. The C-terminal domain unexpectedly folds into a compact domain reminiscent of the RNA-recognition motif fold. The three invariant aspartates of the catalytic triad ligate two of the three active site metals. One of these metals also contacts the adenine ring. Furthermore, conserved, catalytically important residues contact the nucleotide. These contacts, taken together with metal coordination of the adenine base, provide a structural basis for ATP selection by poly(A) polymerase.
Short Name	PolA_pol_RNA-bd_dom