3W5A:
reference: Crystal structures of the calcium pump and sarcolipin in the Mg2+-bound E1 state., Toyoshima C, Iwasawa S, Ogawa H, Hirata A, Tsueda J, Inesi G, Nature. 2013 Mar 14;495(7440):260-4. doi: 10.1038/nature11899. Epub 2013 Mar 3. PMID: 23455422

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