4PFE:
reference: Rational Structure-Based Design of Bright GFP-Based Complexes with Tunable Dimerization., Eshaghi M, Sun G, Gruter A, Lim CL, Chee YC, Jung G, Jauch R, Wohland T, Chen SL, Angew Chem Int Ed Engl. 2015 Nov 16;54(47):13952-6. doi: 10.1002/anie.201506686. , Epub 2015 Oct 8. PMID: 26447926

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