Figure 3. PKCε phosphorylates the third intracellular loop of Na_v1.8.

(A) Schematic diagram illustrating the structural topology common to all eukaryotic sodium channels. (B) Intracellular domains of Na_V1.8 were expressed in bacteria as 6xHis-tagged fusion proteins, and their expression was confirmed by Western blot analysis (left) with an anti-6xHis antibody (N terminus [N], ~24 kDa; L1, ~38 kDa; L2, ~39 kDa; L3, ~11 kDa; C terminus [C], ~35 kDa). Fusion proteins were used in a PKCε assay to determine whether any were PKCε substrates (right). An autoradiogram illustrates that the L3 loop (~11 kDa) is a likely PKCε substrate. Similar amounts of each fusion protein were used in Western blots (left) and kinase assays (right).