Figure 2.

p.Val419Met Blocks K_V6.4 from Reaching the Plasma Membrane Independent of Changes in Steady-State Expression

(A) Immunofluorescence analysis of K_V6.4 localization. In the absence of K_V2.1, K_V6.4 was retained in the cytoplasm (white channel, top panel) and trafficked to the cell membrane in the presence of K_V2.1 (white channel, second row). In contrast, HA-tagged K_V6.4-Met419 did not localize to the cell membrane in the absence or presence of K_V2.1 expression (white channels in the third and fourth rows). Expression of K_V2.1 is demonstrated by the presence or absence of green nuclei, expression of K_V6.4 is displayed directly by HA tag in the white channel, and expression of the IRES vector expressing K_V6.4 is displayed by the presence of the mCherry signal in the red channel. Graphs adjacent to each row display the intensity of the K_V6.4 HA signal along the red line in each respective white channel; note membrane-localized peaks only in K_V6.4 when co-expressed with K_V2.1. Scale bars indicate 10 μm.

(B) HA-tagged K_V6.4 was transiently expressed in the presence or absence of K_V2.1. There was a modest reduction in steady-state stability for K_V6.4-Met419 compared with K_V6.4.

(C) Stability as assessed by densitometry of HA compared with mCherry as a control of transfection efficiency. Error bars indicate standard error. Unpaired t test (*p = 0.04).