Inhibition of voltage-gated calcium channels by sequestration of β subunits

Abstract The auxiliary Ca v β subunit is essential for functional expression of high-voltage activated Ca 2+ channels. Here, we describe a lure sequence designed to sequester the Ca v β subunits in transfected bovine chromaffin cells. This sequence is composed of the extracellular and transmembrane domains of the α chain of the human CD8, the I–II loop of Ca v 2.1 subunit, and EGFP. We showed that expressing the CD8–I–II–EGFP sequence in chromaffin cells led to a >50% decrease in overall Ca 2+ current density. Although this decrease involved all the Ca 2+ channel types (L, N, P/Q, R), the proportion of each type supporting the remaining current was altered. A similar effect was observed after transfection when measuring the functional role of Ca 2+ channels in catecholamine release by chromaffin cells: global decrease of release and change of balance between the different channel types supporting it. Possible explanations for this apparent discrepancy are further discussed.