Fig. 4

Altered activity of SERT variants is differently exhibited in CHO-Flip-In™ stable cells. A) 5-HT transport activity of autism-associated SERT coding variants in CHO-Flip-In™ stable cells. All variants were assayed for 5-HT transport activity. Data reflect mean values ± SEM of 3 separate experiments. Means for variants were compared to hSERT using a One-Way ANOVA followed by Dunnett’s test of individual means against hSERT values with p < 0.05(*) taken as significant. B) Immunoblots of total cell extracts prepared from CHO-Flip-In™ stable cells expressing hSERT or one of the variants described in the study. C) Cell surface expression alterations in hSERT, Gly56Ala, and Ile425Leu. Cell surface transporters were identified by immunoblotting of biotinylated samples. Quantitative estimations of relative D) total and E) surface density of hSERT, Gly56Ala, and Ile425Leu based on densitometry of biotinylation immunoblots. Data reflect mean values of three separate experiments ± SEM. Means were compared with a One-Way ANOVA followed by Dunnett’s test to compare variant surface expression to that achieved with hSERT, with p < .05 taken as significant. F) Gly56Ala and Ile425leu proteins exhibit enhanced catalytic function, with a turnover rate of  ~ 250% or more than that of wildtype SERT. Data reflect mean values of three separate experiments ± SEM. Means were compared with a One-Way ANOVA followed by Dunnett’s test. Figure reproduced from authors’ prior work [79]