Table 1.

A list of genetically encoded Ca²⁺ indicators.

GECIs	Type a	Sensing Module	Reporting Module	Dynamic Range b	Selected Applications	Ref.
Cameleon-1	FRET	CaM-M13	BFP-GFP	70%	HeLa cells	[31]
YC2.1	FRET	CaM-M13	ECFP-EYFP	100%	HeLa cells; hippocampal neuron	[32]
YC3.6	FRET	CaM-M13	ECFP-cp173Venus	560%	HeLa cells; transgenic mice	[33]
YC6.1	FRET	CaM, CKKp	CFP-YFP	200%	HeLa cells; hippocampal neuron	[34]
D3cpV	FRET	CaM-M13	ECFP-cpVenus	510%	Hippocampal neurons	[35]
YC-Nano	FRET	CaM-M13	ECFP-cp173Venus	1450%	Layer 2/3 pyramidal neurons; zebrafish embryo	[36]
TN-L15	FRET	csTnC	CFP-Citrine	140%	HEK293 cells and primary hippocampal neurons	[37]
TN-XL	FRET	csTnC	ECFP-Citrine cp174	400%	Presynaptic motoneuron terminals of transgenic fruit flies	[38]
TN-XXL	FRET	csTnC	ECFP-Citrine Cp174	510%	Drosophila motor neuron boutons; mouse visual cortex	[39]
3xCFP–TnC–cpVenus	FRET	csTnC	3xCFP/cpVenus	1165%	PC12 Cells	[40]
Twitch-2B	FRET	tsTnC	cpVenusCD and mCerulean3	>1000%	Mouse brain and T lymph nodes	[41]
BRAC	BRET	CaM-M13	Venus, RLuc8	60%	HeLa cells and plant leaves	[42]
Nano-lantern (Ca2+)	BRET	CaM-M13	Venus, split RLuc8	300%	HeLa cells and hippocampal neurons	[43]
Camgaroo-1	Single-FP	CaM	EYFP	700%	HeLa cells	[44]
Camgaroo-2	Single-FP	CaM	Citrine	700%	HeLa cells	[45]
Pericam	Single-FP	CaM, M13	cpEYFP	800%	HeLa cells	[46]
GCaMP1.3	Single-FP	CaM, M13	cpEGFP	450%	HEK-293 cells and mouse myotubes	[47]
GCaMP1.6	Single-FP	CaM, M13	cpEGFP	480%	Presynaptic boutons of the Drosophila larval neuromuscular junction	[48]
GCaMP2	Single-FP	CaM, M13	cpEGFP	390%	Beams of parallel fibers and granule cells of frontal cerebellar slices from transgenic mice	[49]
GCaMP3	Single-FP	CaM, M13	cpEGFP	1230%	Flies, worms and mice	[50]
GCaMP4.1	Single-FP	CaM, M13	cpEGFP	ND.	Xenopus laevis	[51]
GCaMP-HS	Single-FP	CaM, M13	cpEGFP	410%	Spinal motor neurons in transgenic zebrafish	[52]
GCaMP5	Single-FP	CaM, M13	cpEGFP	>940%	Cultured neurons and astrocytes, mouse retina; flies, worms, zebrafish and mice	[53]
Fast-GCaMP	Single-FP	CaM, M13	cpEGFP	>650%	Drosophila auditory neurons; superior cervical ganglion and neocortical pyramidal neurons	[54]
GCaMP6	Single-FP	CaM, M13	cpEGFP	>3600%	Cultured neurons; zebrafish, flies and mice	[55]
G-GECO1	Single-FP	CaM, M13	cpEGFP	2500%	HeLa cells; rat hippocampal neurons	[56]
R-GECO1	Single-FP	CaM, M13	cpmApple	1600%	HeLa cells; rat hippocampal neurons	[56]
B-GECO1	Single-FP	CaM, M13	cpEBFP	700%	HeLa cells	[56]
GEX-GECO1	Single-FP	CaM, M13	cpEGFP	2600%	HeLa cells	[56]
GEM-GECO1	Single-FP	CaM, M13	cpEGFP	11,000%	HeLa cells; transgenic C. elegans	[56]
CAR-GECO1	Single-FP	CaM, M13	cpmPulm	2700%	HeLa cells; mouse neocortical slice culture	[57]
R-GECO1.2	Single-FP	CaM, M13	cpmPulm	3300%	HeLa cells and INS-1 cells	[57]
O-GECO1	Single-FP	CaM, M13	cpmOrange	14,600%	HeLa cells	[57]
R-CaMP1.07	Single-FP	CaM, M13	cpmApple	2870%	HeLa cells and hippocampal pyramidal neurons	[58]
Y-GECO1	Single-FP	CaM, M13	cpmPapaya0.4	20,000%	HeLa cells and rat hippocampal neurons	[59]
REX-GECO1	Single-FP	CaM, M13	cpmApple	10,000%	Organotypic hippocampal slice cultures; albino tadpoles	[60]
GR-GECO	Single-FP	CaM, M13	cpmMapple145	450%	HeLa cells and rat hippocampal neurons	[61]
LAR-GECO	Single-FP	CaM, M13	cp146mApple	1000%	HeLa, HEK293, U2OS cells and rat hippocampal neurons	[62]
BCaMP1c	Single-FP	CaM, M13	cpBFP	200%	ND	[63]
CyCaMP1a	Single-FP	CaM, M13	cpCFP	260%	ND	[63]
YCaMP1b	Single-FP	CaM, M13	cpYFP	920%	HEK293 cells	[63]
RCaMP1h	Single-FP	CaM, M13	cp159mRuby	1050%	HEK293 cells, neurons; worms, fly larvae, and zebrafish	[63]
RA-CaM-B-M13-GA	FPX	CaM, M13	RA, B, GA	ND	HeLa cells	[64]

^aFRET (Förster Resonance Energy Transfer) and single-FP (Fluorescent protein) types indicate ratiometric and intensometric response, respectively;

^bDynamic range here refers to the ratio of optical response in the fully activated indicator to the measured signal in the off state. Unless otherwise specified in the main text, the reported value refers to a positive relationship between Ca²⁺ and fluorescence intensity or ratio.