TABLE 1.

Sensitized emission lifetimes and corresponding distances measured from receptors tagged with donor and acceptor fluorophores

Construct/expression system	τD	τDA	R
	μs	μs	Å
L139C/Q340C
Oocytes
pH 8	1648 ± 1.2	350 ± 5.4	29 ± 0.07
pH 6	1672 ± 2.4	268 ± 4.3	27 ± 0.07
HEK293T cells
pH 8	1555 ± 1.2	293 ± 3.0	28 ± 0.04
pH 6	1575 ± 1.7	225 ± 1.3	26 ± 0.02
T130C/Q340C
Oocytes
pH 8	1575 ± 1.1	257 ± 2.0, 560 ± 8	27 ± 0.03, 32 ± 0.4
pH 6	1588 ± 1.3	173 ± 1.7, 630 ± 10	25 ± 0.06, 33 ± 0.5
HEK293T cells
pH 8	1511 ± 1.2	252 ± 8, 520 ± 7	28 ± 0.1, 32 ± 0.4
pH 6	1589 ± 1.4	183 ± 3, 650 ± 9	26 ± 0.07, 33 ± 0.5
L139C/Q340C/D238A/E239A
HEK293T cells
pH 8	1672 ± 0.6	304 ± 1.8	28 ± 0.02
pH 6	1745 ± 0.6	312 ± 2.06	28 ± 0.03
L139C/Q340C/D238A/E239A/D260A
HEK293T cells
pH 8	1666 ± 0.6	293 ± 1.1	28 ± 0.01
pH 6	1752 ± 0.6	293 ± 1.3	28 ± 0.02