1Y51:
reference: The HPr proteins from the thermophile Bacillus stearothermophilus can form domain-swapped dimers., Sridharan S, Razvi A, Scholtz JM, Sacchettini JC, J Mol Biol. 2005 Feb 25;346(3):919-31. Epub 2004 Dec 23. PMID: 15713472

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