Coelenterazine 400a (hydrochloride)

Coelenterazine 400a is a bisdeoxy derivative of coelenterazine that displays an emission maximum of 395 nm following conversion by Renilla luciferase (Rluc).[1],[2] It is used in bioluminescence resonance energy transfer 2 (BRET2) protocols, whereas coelenterazine h, which displays an emission maximum of 475 nm upon conversion by Rluc, is used in BRET1 protocols.3 Coelenterazine 400a is commonly paired with class 1 and 3 GFP acceptors, including GFP2 and GFP10.[2],[3] BRET2 assays are commonly used in evaluating protein-protein interactions, including those involved in G protein-coupled receptor signaling.[1],[2],[4]

Reference:
[1]. Bertrand, L., Parent, S., Caron, M., et al. The BRET2/arrestin assay in stable recombinant cells: A platform to screen for compounds that interact with G protein-couple receptors (GPCRS). J. Recept. Signal Transduct. Res. 22(1-4), 533-541 (2002).
[2]. Galés, C., Rebois, R.V., Hogue, M., et al. Real-time monitoring of receptor and G-protein interactions in living cells. Nat. Methods 2(3), 177-184 (2005).
[3]. Pfleger, K.D., and Eidne, K.A. Illuminating insights into protein-protein interactions using bioluminescence resonance energy transfer (BRET). Nat. Methods 3(3), 165-174 (2006).
[4]. Huang, Q., Acha, V., Yow, R., et al. Bioluminescence measurements in mice using a skin window. J. Biomed. Opt. 12(5):054012, (2007).