. Author manuscript; available in PMC: 2021 Feb 9.

Published in final edited form as: Biochemistry. 2020 Sep 10;59(38):3594–3614. doi: 10.1021/acs.biochem.0c00576

Table 3.

Pharmacological Parameters of Protons at GPR68 in the Presence of Metal Ions^a

metal and concentrations		pEC₅₀ (pH)	E_max (%)	Hill slope
Ca²⁺	0	6.76 ± 0.01	99.5 ± 1.7	2.11 ± 0.09
	30 μM	6.76 ± 0.01	108.3 ± 2.1	2.16 ± 0.11
	100 μM	6.83 ± 0.01	101.2 ± 2.1	2.35 ± 0.14
	300 μM	6.84 ± 0.01	116.6 ± 2.6	2.31 ± 0.15
	1 mM	6.87 ± 0.02	133.1 ± 2.9	2.20 ± 0.14
	3 mM	6.86 ± 0.02	138.6 ± 3.4	2.19 ± 0.16
Mg²⁺	0	6.69 ± 0.01	99.9 ± 1.5	2.48 ± 0.10
	30 μM	6.66 ± 0.01	103.2 ± 2.0	2.30 ± 0.11
	100 μM	6.69 ± 0.01	94.7 ± 1.8	2.38 ± 0.12
	300 μM	6.70 ± 0.02	102.3 ± 2.6	2.29 ± 0.15
	1 mM	6.70 ± 0.02	115.1 ± 3.2	2.18 ± 0.15
	3 mM	6.72 ± 0.02	115.7 ± 3.4	2.07 ± 0.15
Cd²⁺	0	6.87 ± 0.01	99.5 ± 1.1	2.55 ± 0.10
	10 nM	7.01 ± 0.01	105.0 ± 1.2	2.52 ± 0.11
	30 nM	7.31 ± 0.01	104.7 ± 1.0	2.31 ± 0.11
	100 nM	7.61 ± 0.01	128.4 ± 1.3	2.06 ± 0.12
	300 nM	7.92 ± 0.02	141.4 ± 1.7	1.99 ± 0.13
	1000 nM	8.22 ± 0.01	149.7 ± 1.9	1.54 ± 0.10
Co²⁺	0	6.89 ± 0.01	99.8 ± 1.2	3.03 ± 0.13
	10 nM	7.08 ± 0.01	106.5 ± 1.2	2.24 ± 0.09
	30 nM	7.34 ± 0.01	108.6 ± 1.1	2.55 ± 0.12
	100 nM	7.58 ± 0.01	133.0 ± 1.4	2.41 ± 0.13
	300 nM	7.84 ± 0.01	152.0 ± 1.7	2.10 ± 0.11
	1000 nM	8.14 ± 0.01	154.3 ± 1.7	2.27 ± 0.13
Fe²⁺	0	6.79 ± 0.01	100.2 ± 1.1	3.11 ± 0.12
	0.3 μM	6.87 ± 0.01	103.8 ± 1.0	2.63 ± 0.08
	1 μM	7.02 ± 0.01	98.1 ± 0.8	2.58 ± 0.08
	3 μM	7.25 ± 0.01	107.3 ± 1.1	3.49 ± 0.19
	10 μM	7.31 ± 0.01	115.3 ± 1.2	3.60 ± 0.22
	30 μM	7.34 ± 0.01	116.8 ± 1.3	4.42 ± 0.33
Mn²⁺	0	6.76 ± 0.01	99.2 ± 1.0	2.53 ± 0.08
	0.1 μM	6.77 ± 0.01	102.2 ± 1.2	2.00 ± 0.06
	0.3 μM	6.93 ± 0.01	90.3 ± 1.2	1.73 ± 0.06
	1 μM	7.22 ± 0.01	91.5 ± 1.3	1.61 ± 0.07
	3 μM	7.53 ± 0.01	101.1 ± 1.2	1.66 ± 0.07
	10 μM	7.84 ± 0.01	106.9 ± 1.1	1.85 ± 0.09
Ni²⁺	0	6.85 ± 0.01	100.2 ± 1.6	2.46 ± 0.10
	10 nM	6.96 ± 0.02	103.2 ± 2.3	1.75 ± 0.09
	30 nM	7.26 ± 0.02	91.9 ± 1.5	1.85 ± 0.09
	100 nM	7.55 ± 0.01	112.5 ± 1.3	2.16 ± 0.10
	300 nM	7.80 ± 0.01	134.0 ± 1.8	2.31 ± 0.15
	1000 nM	8.09 ± 0.01	143.6 ± 1.9	2.32 ± 0.15
Zn²⁺	0	6.78 ± 0.01	98.5 ± 1.3	2.46 ± 0.11
	10 nM	6.79 ± 0.01	98.6 ± 1.4	2.48 ± 0.12
	30 nM	6.83 ± 0.01	91.1 ± 1.6	2.33 ± 0.14
	100 nM	6.96 ± 0.02	96.4 ± 1.8	2.06 ± 0.14
	300 nM	7.17 ± 0.02	98.8 ± 1.4	2.06 ± 0.12
	1000 mM	7.27 ± 0.01	100.9 ± 1.3	2.10 ± 0.12

Proton concentration response curves are presented in Figure 5. Parameters were extracted from curve fitting to the Prism 8.4 build-in four-parameter logistic function.