Table 1 Properties of CEPIA variants.

From: Imaging intraorganellar Ca2+ at subcellular resolution using CEPIA

Probe

Ca 2+

ε (mM–1 cm–1) (λABS*)

λ Ex *

Φ ( λEm*)

Brightness† (mM–1 cm–1)

p K a ‡

Dynamic range §

K d for Ca 2+

Hill coefficient

G-CEPIA1er

−

36 (402), 3 (498)

499

0.19 (512)

0.5

8.7

4.7±0.3||

672±23 μM||

1.95±0.07||

 

+

33 (401), 10 (497)

498

0.40 (511)

3.4

8.0

   

G-GECO1.1

−

35 (401), 2 (500)

499

0.20 (514)

0.4

8.8

14.7±1.6

363±4 nM

3.38±0.10

 

+

24 (397), 26 (497)

498

0.46 (513)

10.5

7.4

   

R-CEPIA1er

−

25 (445), 5 (576)

570

0.09 (593)

0.5

8.9

8.8±0.7

565±58 μM

1.70±0.04

 

+

15 (448), 35 (562)

561

0.18 (584)

6.2

6.5, 9.0

   

R-GECO1

−

27 (445), 7 (576)

565

0.06 (594)

0.4

8.9

15.6±4.1

142±17 nM

2.05±0.12

 

+

58 (562)

560

0.20 (584)

11.6

6.4

   

GEM-CEPIA1er

−

36 (401)

381, 395

0.26 (510)

9.4

6.1

21.7±0.6

558±14 μM

1.37±0.01

 

+

36 (391)

381, 394

0.21 (462)

7.6

6.5, 10.6

   

GEM-GECO1

−

34 (395)

387, 395

0.31 (510)

10.7

6.1

67.5±10.9

306±0.4 nM

2.55±0.02

 

+

35 (391)

387, 390

0.18 (462)

6.2

6.1, 10.1

   
  1. *λABS, λEx and λEm are the maximum wavelength of absorption, fluorescence excitation and fluorescence emission spectra, respectively.
  2. †Brightness is the product of molar extinction coefficient (ε) and quantum yield (Φ).
  3. ‡pKa is determined as the pH at half-maximal fluorescence intensity calculated by fitting Hill equation to each plot. As for R-CEPIA1er, GEM-GECO1 and GEM-CEPIA1er, pKa is calculated by double Hill equation (See Methods).
  4. §Dynamic range indicates the ratio of the maximum to minimum fluorescence intensity (Fmax/Fmin) or fluorescence ratio (Rmax/Rmin) (See Methods).
  5. ||Mean±s.e.m.
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