4JDK:
reference: Identification of a major determinant for serine-threonine kinase phosphoacceptor specificity., Chen C, Ha BH, Thevenin AF, Lou HJ, Zhang R, Yip KY, Peterson JR, Gerstein M, Kim PM, Filippakopoulos P, Knapp S, Boggon TJ, Turk BE, Mol Cell. 2014 Jan 9;53(1):140-7. doi: 10.1016/j.molcel.2013.11.013. Epub 2013, Dec 26. PMID: 24374310

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