4A4M:
reference: Stabilized G protein binding site in the structure of constitutively active metarhodopsin-II., Deupi X, Edwards P, Singhal A, Nickle B, Oprian D, Schertler G, Standfuss J, Proc Natl Acad Sci U S A. 2012 Jan 3;109(1):119-24. Epub 2011 Dec 23. PMID: 22198838

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