Figure S4. Optically tracked... | Rockefeller University Press

Figure S4.

Optically tracked voltage-dependent rearrangements of the individual VSD in human CaV1.1 R174W mutant. (A–D) Simultaneously recorded Ba2+ currents (black) and fluorescence signals reporting local protein structural changes (colored traces) from human R174W CaV1.1 channels (α1S+β1a+Stac3) expressed in Xenopus oocytes are shown. The topology above the recorded traces highlights the position of the R174W mutation (innermost gating charge of S4 in VSD-I; yellow star) and the location of the conjugated thiol-reactive fluorophore (pink rhodamine molecule). Note that, for VSD-I (A), larger depolarizations are needed to achieve voltage sensor activation as compared with WT VSD-I (Fig. S4 A versus Fig. 3 A, blue traces), since the neutralization of one of its gating charges (R174W) impaired its voltage-dependent activation (Fig. 5 B). Note that the current scale in A is 10-fold bigger than in B, C, and D.

Optically tracked voltage-dependent rearrangements of the individual VSD in human Ca_V1.1 R174W mutant. (A–D) Simultaneously recorded Ba²⁺ currents (black) and fluorescence signals reporting local protein structural changes (colored traces) from human R174W Ca_V1.1 channels (α_1S+β_1a+Stac3) expressed in Xenopus oocytes are shown. The topology above the recorded traces highlights the position of the R174W mutation (innermost gating charge of S4 in VSD-I; yellow star) and the location of the conjugated thiol-reactive fluorophore (pink rhodamine molecule). Note that, for VSD-I (A), larger depolarizations are needed to achieve voltage sensor activation as compared with WT VSD-I (Fig. S4 A versus Fig. 3 A, blue traces), since the neutralization of one of its gating charges (R174W) impaired its voltage-dependent activation (Fig. 5 B). Note that the current scale in A is 10-fold bigger than in B, C, and D.