FIGURE 6.

Increased SUMOylation augments HCN2 channel surface expression. GFP-HCN2 channel cell surface expression was monitored using a biotinylation assay. Hek-HCN2 cells were transiently transfected with mCherry alone or mCherry + SUMO + Ubc9. Two days after transfection cultures were biotinylated and cell surface proteins were isolated from cell lysates using Neutravidin. Both the intracellular and cell surface fractions were run on a WB and probed with antibodies recognizing GFP, Na⁺/K⁺-ATPase, and Actin. (A) Representative WBs. (B) Plots depicting average normalized GFP-HCN2 channel surface expression (GFP doublet OD ÷ Na⁺/K⁺-ATPase OD). The treatment and the n are shown below the graph. Each n represents a single plate that was transfected, biotinylated and carried through the experiment to produce a single lane on a WB. Asterisk indicates significant difference between treatment groups (Student’s t-test, p < 0.05).