Fig. 2

Biochemical and functional analysis of Kv4.3 dupRVF mutant channel. a Sequence comparison of the S4 transmembrane segment for Kv1.2 and Kv4.3 WT and dupRVF mutant channels. Insertion of RVF at amino acid position 296–298 is underlined. b Co-immunostaining of Kv4.3 WT or dupRVF mutant (red) and golgin97 (Golgi apparatus marker; green) in transfected HeLa cells. Nuclei were stained using Dapi (blue). Scale bar = 50 μm. c Percentage of remaining Kv4.3 protein after 0, 3 h or 6 h cycloheximide (CHX) treatment. In absence of KChIP, the remaining dupRVF mutant protein was significantly lower compare with the WT at 3 h (dupRVF: 43.9 ± 0.9 % vs WT: 93.1 ± 6 %) and at 6 h (dupRVF: 24.4 % vs WT: 62.2 ± 5 %). In presence of KChIP, no significant differences were detected at 3 h (dupRVF: 100.4 ± 15 % vs WT: 97.2 ± 11 %) and at 6 h (dupRVF: 105.2 ± 8 % vs WT: 91.3 ± 10 %). Graph represents the Western blot densitometries and is representative of 3 independent experiments. Significant differences are depicted by the Student’s t test (p > 0.01). d Averaged current density-voltage relationships of Kv4.3 WT and dupRVF mutant, expressed in CHO cells with KChIP2 (ratio 1:1). e Normalized conductance-voltage relationship for Kv4.3 WT and dupRVF mutant. f Voltage-dependent inactivation curves of Kv4.3 WT and dupRVF. Data were fitted to Boltzmann function (solid curves) and parameters summarized in Table 1