Analytical Sciences

Bioluminescent Indicators for Ca²⁺ Based on Split Renilla Luciferase Complementation in Living Cells

Asami KAIHARA,*^,** Yoshio UMEZAWA,**^,*** and Tetsushi FURUKAWA*

* Department of Bio-Informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda, Tokyo 101-0062, Japan
** Department of Chemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
*** Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20 Shinmachi, Nishitokyo, Tokyo 202-8585, Japan

Genetically encoded bioluminescent indicators for intracellular Ca²⁺ are described here with CaM-M13 interaction-induced complementation of split Renilla luciferase. The Ca²⁺-induced interaction between CaM and M13 leads to complementation of the N- and C-terminal halves of split Renilla luciferase in living cells. This intramolecular interaction results in the spontaneous and simultaneous emission of bioluminescence split Renilla luciferase. This is how intracellular Ca²⁺ is illuminated with the intramolecular complementation of split Renilla luciferase. The Ca²⁺-dependent spontaneous and simultaneous emission of bioluminescence promises to reveal Ca²⁺ dynamics in living cells, and also in vivo using the present indicators.

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