Dr. Buraei's Research Lab
Functional Characterization of Two Calcium Channel Mutations Associated with Epilepsy
Z. Buraei., S. Allam., G. Suppa., P. Hanson., L. Yorke.
Voltage-gated calcium channels (VGCC) are protein complexes found on the membranes of nerve and heart cells, where they control cell excitability. They have a pore-forming α1 subunit, but also require the auxiliary β subunit, which is required for both channel trafficking and for normal channel activation and inactivation. Interestingly, mutations in one of the four β subunits, β3, were found in a cohort of epileptic patients, but not unaffected individuals. The functional impact of two of these mutations (E53K and Q131L) are unknown and we studied them using site-directed mutagenesis, in-vitro RNA synthesis, and two-electrode voltage clamp (TEVC) recordings to compare the electrical currents from Xenopus oocytes expressing VGCC with either E53K, Q131L, or the wild-type β3 subunit. We found the E53K mutant channels have significantly reduced currents. In contrast, the Q131L β3 mutant that we characterized was not different from the WT in a discernable way.
Figure 1. Structure of voltage-gated calcium channel. This figure shows all the necessary subunits that are required for proper channel function. Voltage-gated calcium channels are composed of four subunits, and they are the α1, β, α2δ, and the γ subunits, of which only the β subunit is ubiquitous (Buraei et al., 2010).