Figure 5.

Evaluation of Gα_o-Mediated Signaling in NG108-15 Cell Calcium-Current Generation

(A) Representative traces of voltage-gated calcium currents generated in NG108-15 cells expressing WT (left) or p.Thr191_Phe197del altered (right) Gα_o1. Black and red traces represent the currents before and 3 min after application of 10 μM norepinephrine, respectively.

(B) Current densities of the calcium currents before norepinephrine treatment in cells expressing WT or altered Gα_o1. Scatter plots represent the densities in individual cells. Red squares and bars represent the means and SEMs, respectively, of the densities in individual cell groups (WT, n = 8; p.Gly203Thr, n = 7; p.Asp174Gly, n = 8; p.Thr191_Phe197del, n = 7; p.Ile279Asn, n = 7). Compared with that in cells expressing WT Gα_o1, the current density in cells expressing p.Thr191_Phe197del increased significantly (^∗p < 0.05 by Dunnett’s post hoc test). The densities in the cells expressing other altered proteins did not vary significantly.

(C) Comparison of norepinephrine-induced inhibition of calcium currents in cells expressing altered Gα_o1. Each error bar represents the mean and SEM of the percent decrease in current density induced by application of 10 μM norepinephrine. Paired t tests indicated that the inhibition induced by norepinephrine was significant in cells expressing WT (n = 8) and p.Gly203Thr (n = 7), p.Asp174Gly (n = 8), and p.Ile279Asn (n = 7) altered proteins (^∗∗p < 0.01 and ^∗p < 0.05), but not in cells expressing p.Thr191_Phe197del (n = 7). Although there was some tendency for decreased inhibition in cells expressing altered proteins, the tendency did not reach statistical significance compared with that in WT-expressing cells (p = 0.41 by ANOVA).