FIGURE 2.
Cav3 accelerates hERG degradation and enhances hERG-Ub interaction. A, time-dependent decrease in IhERG in brefeldin A (BFA)-treated cells transfected with or without Cav3. hERG tail currents at each recording time point in both groups are summarized on the left, and the relative current amplitudes normalized to the initial values are summarized on the right below the traces (n = 6–9 cells at each point). B, Cav3 interacting with hERG channels. Cav3 or hERG was detected in proteins precipitated with an anti-hERG or anti-Cav3 antibody from whole cell proteins extracted from hERG-HEK cells 24 h after Cav3 transfection (n = 6 or 8, respectively). A fraction of proteins used for the pulldown assay was also immunoblotted for hERG expression in lane 1 of the right panel in B. C, Cav3-enhanced hERG-Ub interaction. hERG was detected in proteins precipitated with an anti-Ub antibody from whole cell proteins extracted from hERG-HEK cells but not from HEK cells transfected with Cav3. Compared with pcDNA3 transfection, Cav3 expression increases the hERG-Ub interaction (n = 9). D, Nedd4-2 targeting PPXY motif in the hERG channel. Alignment of the PY motif (bold) of the Nav1.5 channel, ENaC subunits, and the hERG channel (GenBank numbers in italics) is shown. Position number indicates the location of first proline (P) in the PPXY sequence.