3QAL:
reference: A conserved Glu-Arg salt bridge connects coevolved motifs that define the eukaryotic protein kinase fold., Yang J, Wu J, Steichen JM, Kornev AP, Deal MS, Li S, Sankaran B, Woods VL Jr, Taylor SS, J Mol Biol. 2012 Jan 27;415(4):666-79. Epub 2011 Nov 25. PMID: 22138346

This OCA Structure page
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