Figure 8.

Heteromerization between KDC1 and KDC2 channel subunits. (A) KDC1 is targeted to the membrane when it is coexpressed with KDC2. Confocal laser-scanning microscopical analyses on oocytes expressing KDC2/KDC1-EGFP microinjected with Fura Red. The left column shows the fluorescence collected from an x-y plane of the oocyte. This panel shows a green layer (belonging to GFP signal) external to the red one (belonging to Fura Red signal); the yellow layer is due to the colocalization of the two fluorophores. The right column shows the results obtained by a spectral unmixing analysis, applied on every oocyte injected. Traces show normalized fluorescence intensity for a particular ROI of the two fluorophores as a function of the distance z (0 coincides with the slide plane and 40 μm with the most internal plane of the oocyte reached). The inset shows a magnification of the distance between the two fluorophores. The mean distance measured between the two peaks, d(EGFP-Fura Red), is 2.1 ± 0.3 μm. Data are mean values ± SE from more than 20 ROI on seven independent oocytes. (B) Upper panel: current traces recorded in oocytes injected with KDC2 and KDC2 coinjected with KDC1 and the truncated constructs KDC1(cNBD) and KDC1(ΔK_HA). Middle panel: comparison ± Zn²⁺ at −160 mV for the same constructs. Lower panel: mean values (± SE) of the change of the current induced by 1 mM Zn²⁺ at −160 mV (I_zinc-I_control)/I_control for the different constructs.