. 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 1.

Pharmacological Parameters for the Proton Concentration-Response Curves in the Absence and Presence of Ca²⁺ and Mg²⁺ and EDTA^a

receptor	condition	basal (%)	E_max (%)	potency (pH)	Hill slope
GPR4	without Ca²⁺/Mg²⁺	0	100	8.11 ± 0.01	5.90 ± 0.31
GPR4	with 1 mM Ca²⁺/Mg²⁺	7.0 ± 2.5	127.2 ± 2.3	8.08 ± 0.01	5.14 ± 0.50
GPR65	without Ca²⁺/Mg²⁺	0	100	7.49 ± 0.01	4.31 ± 0.23
GPR65	with 1 mM Ca²⁺/Mg²⁺	0.0 ± 2.5	114.8 ± 3.2	7.48 ± 0.01	4.85 ± 0.52
GPR68	without Ca²⁺/Mg²⁺	0	100	6.74 ± 0.01	2.31 ± 0.06
GPR68	with 1 mM Ca²⁺/Mg²⁺	2.3 ± 1.9	129.8 ± 2.6	6.81 ± 0.01	2.37 ± 0.16
GPR68	control	0 (shared globally)	98.2 ± 1.5	6.81 ± 0.01	2.66 ± 0.13
	1 μM EDTA		96.5 ± 1.6	6.72 ± 0.01	2.62 ± 0.13
	3 μM EDTA		94.8 ± 1.6	6.72 ± 0.01	2.64 ± 0.13
	10 μM EDTA		104.3 ± 1.9	6.68 ± 0.01	2.63 ± 0.13
	30 μM EDTA		103.1 ± 2.2	6.65 ± 0.01	2.56 ± 0.14
	100 μM EDTA		100.5 ± 2.5	6.63 ± 0.01	5.23 ± 0.15

Concentration-response curves are presented in Figure 2. Parameters were retrieved from fittings with pooled and normalized results using the Prism 8.4 built-in four-parameter logistic function.