Table 1.

Mean normalized FRET efficiency ± SEM for each TAG position relative to each cysteine (ACCuRET) or the membrane (memFRET) measured at pH 8 and pH 6. Distances were calculated with Equation 4.

			pH 8				pH 6
	TETAC Position	TAG position	mean normalized FRET efficiency	SEM	N	Distance (Å)	mean normalized FRET efficiency	SEM	N	Distance (Å)
ACCuRET	C469	E8TAG	0.20	0.03	13	22	0.27	0.01	17	20
		G11TAG	0.18	0.02	11	23	0.32	0.02	6	20
		Q14TAG	0.29	0.02	18	20	0.43	0.02	15	18
		S24TAG	0.45	0.02	10	18	0.57	0.01	8	16
		I33TAG	0.37	0.02	21	19	0.58	0.01	17	16
		A44TAG	0.43	0.02	6	19	0.27	0.02	14	20
	C477	G11TAG	0.26	0.02	20	21	0.38	0.03	7	19
		Q14TAG	0.28	0.02	11	21	0.31	0.03	12	20
		S24TAG	0.35	0.02	22	20	0.49	0.04	9	17
	C485	E8TAG	0.11	0.02	22	25	0.26	0.03	13	21
		G11TAG	0.28	0.02	14	21	0.59	0.02	10	16
		Q14TAG	0.21	0.04	27	22	0.58	0.02	23	16
		S24TAG	0.32	0.04	16	19	0.57	0.01	13	16
	C505	E8TAG	0.27	0.01	12	21	0.37	0.02	13	19
		Q14TAG	0.41	0.02	6	19	0.43	0.03	13	18
	C515	E8TAG	0.08	0.01	14	26	0.24	0.01	9	21
		Q14TAG	0.20	0.02	7	22	0.45	0.01	7	18
ACCuRET Zn2+ controls	C469	E8TAG	−0.06	0.01	6	N/A	0.04	0.01	8	N/A
		G11TAG	−0.03	0.01	8	N/A	−0.05	0.01	10	N/A
memFRET	N/A	E8TAG	0.42	0.03	11	10	0.40	0.03	14	11
		G11TAG	0.46	0.03	9	10	0.48	0.01	15	9
		Q14TAG	0.44	0.02	10	10	0.60	0.03	7	6
		S24TAG	0.74	0.04	4	≤ 5	0.72	0.02	24	≤ 5
		I33TAG	0.52	0.02	8	8	0.71	0.03	9	≤ 5
	N/A	S464TAG	0.69	0.02	15	≤ 5	0.63	0.02	10	≤ 5
		M505TAG	0.75	0.02	8	≤ 5	0.48	0.02	14	9
MemFRET Zn2+ controls	N/A	E8TAG	−0.13	0.01	8	N/A	−0.15	0.02	9	N/A
		G11TAG	−0.03	0.01	8	N/A	0.01	0.01	9	N/A
		S464TAG	0.06	0.04	6	N/A	0.01	0.03	10	N/A
		M505TAG	−0.12	0.04	6	N/A	−0.12	0.03	9	N/A