1KBU:
reference: The order of strand exchanges in Cre-LoxP recombination and its basis suggested by the crystal structure of a Cre-LoxP Holliday junction complex., Martin SS, Pulido E, Chu VC, Lechner TS, Baldwin EP, J Mol Biol 2002 May 24;319(1):107-27. PMID: 12051940

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