FIGURE 8.

The ER retention signal within the KID inhibits total and surface expression of Kv4.3. A and C, representative Western blots of total (A) and surface (C) proteins from HEK 293 cells transiently transfected with plasmids encoding Kv4.3 with WT KChIP4a or KChIP4a mutants. For quantification, the intensities of the Kv4.3 bands were measured and normalized, to endogenous actin (for total) or TransR (for surface) in the same lane and subsequently to Kv4.3 co-expressed with WT KChIP4a in the same blot. B and D, quantification analysis of total (B) and surface (D) expression levels of Kv4.3 co-expressed with WT KChIP4a or KChIP4a mutants. Values are mean ± S.E. (error bars); n = 4–6 blots. Statistical analysis was performed using one-way analysis of variance followed by Tukey's post hoc test, and statistical significance was assessed as follows. **, p < 0.01; ***, p < 0.001. E, representative Western blot of total proteins from HEK 293 cells transiently transfected with plasmids encoding KChIP4a-3xFLAG or KChIP4aΔ2–34-3xFLAG. F, quantification analysis of total expression levels of KChIP4a-3xFLAG and KChIP4aΔ2–34-3xFLAG, indicating reduced expression of KChIP4a as compared with KChIP4aΔ2–34. G, quantification analysis of relative current change in oocytes expressing Kv4.3 co-expressed with KChIP4a mutants normalized to Kv4.3 co-expressed with WT KChIP4a. Values are mean ± S.E.; n = 8–26 oocytes; ***, p < 0.001.