1WA9:
reference: Crystal structure and interactions of the PAS repeat region of the Drosophila clock protein PERIOD., Yildiz O, Doi M, Yujnovsky I, Cardone L, Berndt A, Hennig S, Schulze S, Urbanke C, Sassone-Corsi P, Wolf E, Mol Cell. 2005 Jan 7;17(1):69-82. PMID: 15629718

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