3EBJ:
reference: Crystal structure of an avian influenza polymerase PA(N) reveals an endonuclease active site., Yuan P, Bartlam M, Lou Z, Chen S, Zhou J, He X, Lv Z, Ge R, Li X, Deng T, Fodor E, Rao Z, Liu Y, Nature. 2009 Apr 16;458(7240):909-13. Epub 2009 Feb 4. PMID: 19194458

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