Tq-Ca-FLITS is a turquoise fluorescence lifetime-based biosensor for quantitative imaging of intracellular Ca[2+]. It is a fusion protein composed of the M13 calmodulin-binding peptide, a circularly permuted form of mTurquoise2 (that also includes a F146Y mutation) and calmodulin. For detailed kinetic and spectral properties, see PMID:34887382.