Table 1.

Properties of some G-CAMP based sensors and their cilia targeting derivatives.

Name	DRa	Kd (Ca2+) (nM)	Comments	References
General cytosolic GECI
G-CaMP	4.3 ×	235	Weak fluorescence at physiological temperatures compared to EGFP	Souslova et al. (2007) Nakai et al. (2001)
G-CaMP3	12 ×	540	1.3 × higher affinity to Ca2+ and 3 × more dynamic range compared to G-CaMP	Zhao et al. (2011)
G-GECO1.0	25 ×	750	2 × higher dynamic range compared to G-CaMP3	Zhao et al. (2011) Pala et al. (2018)
G-GECO1.2	23 ×	1150	Sensitive to a range of 1–10 μM Ca2+	Zhao et al. (2011)
G-CaMP6s	23 ×	144	10 × higher sensitivity and increased dynamic range than G-CaMP3	Chen et al. (2013)
Cilia targeting GECI
Arl13b-G-CaMP6	23 ×	144	Arl13b is used to localize G-CaMP6 to the cilioplasm	Yuan, Zhao, Brueckner, and Sun (2015) Chen et al. (2013)
ALC (Arl13b fused to YC3.6)	5.6 ×	250	FRET-based sensor with ECFP & cpVenus (donor-acceptor)	Lee et al. (2015) Nagai, Yamada, Tominaga, Ichikawa, and Miyawaki (2004)
Arl13b-mCherry-GECO1.2	–	450	Reaches saturation at 800 nM Ca2+	Delling et al. (2016)
CTS-G-CaMP3	12 ×	542	Contains the intracellular C-tail of fibrocystin, Pkhd1 (C1–68) for ciliary localization of the sensor	Jin et al. (2014)
5HT6-mCherry-G-GECO1.0	25 ×	750	mCherry allows constant cilia fluorescence and ratiometric analysis	Su et al. (2013) Pala et al. (2018)

^aDynamic Range (DR) is defined as the ratio of emission intensities (ΔF/F₀) for intensiometric GECOs and the ratio of emission ratios (ΔEGFP/EGFP₀)/(ΔmCherry/mCherry₀) for 5HT6-mCherry-G-GECO1.0. For ALC, the dynamic range is derived from (E_max E_min)/E_min, where E is FRET efficiency.