2HQ8:
reference: Crystal structure of coelenterazine-binding protein from Renilla muelleri at 1.7 A: why it is not a calcium-regulated photoprotein., Stepanyuk GA, Liu ZJ, Markova SS, Frank LA, Lee J, Vysotski ES, Wang BC, Photochem Photobiol Sci. 2008 Apr;7(4):442-7. Epub 2008 Feb 19. PMID: 18385886

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