3GEC:
reference: Structural and functional analyses of PAS domain interactions of the clock proteins Drosophila PERIOD and mouse PERIOD2., Hennig S, Strauss HM, Vanselow K, Yildiz O, Schulze S, Arens J, Kramer A, Wolf E, PLoS Biol. 2009 Apr 28;7(4):e94. PMID: 19402751

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