1QEX:
reference: The structure of bacteriophage T4 gene product 9: the trigger for tail contraction., Kostyuchenko VA, Navruzbekov GA, Kurochkina LP, Strelkov SV, Mesyanzhinov VV, Rossmann MG, Structure Fold Des 1999 Oct 15;7(10):1213-22. PMID: 10545330

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